elab_expr.cc

/*
 * Copyright (c) 1999-2024 Stephen Williams (steve@icarus.com)
 * Copyright CERN 2013 / Stephen Williams (steve@icarus.com)
 *
 *    This source code is free software; you can redistribute it
 *    and/or modify it in source code form under the terms of the GNU
 *    General Public License as published by the Free Software
 *    Foundation; either version 2 of the License, or (at your option)
 *    any later version.
 *
 *    This program is distributed in the hope that it will be useful,
 *    but WITHOUT ANY WARRANTY; without even the implied warranty of
 *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *    GNU General Public License for more details.
 *
 *    You should have received a copy of the GNU General Public License
 *    along with this program; if not, write to the Free Software
 *    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 */

# include "config.h"
# include  <typeinfo>
# include  <cstdlib>
# include  <cstring>
# include  <climits>
# include "compiler.h"

# include  "PPackage.h"
# include  "pform.h"
# include  "netlist.h"
# include  "netclass.h"
# include  "netenum.h"
# include  "netparray.h"
# include  "netvector.h"
# include  "discipline.h"
# include  "netmisc.h"
# include  "netdarray.h"
# include  "netqueue.h"
# include  "netstruct.h"
# include  "netscalar.h"
# include  "util.h"
# include  "ivl_assert.h"
# include  "map_named_args.h"

using namespace std;

bool type_is_vectorable(ivl_variable_type_t type)
{
      switch (type) {
	  case IVL_VT_BOOL:
	  case IVL_VT_LOGIC:
	    return true;
	  default:
	    return false;
      }
}

static ivl_nature_t find_access_function(const pform_scoped_name_t &path)
{
      if (path.package || path.name.size() != 1)
	    return nullptr;
      return access_function_nature[peek_tail_name(path)];
}

/*
 * Look at the signal to see if there is already a branch that
 * connects the sig to the gnd. If there is, then return it. If not,
 * return 0.
 */
static NetBranch* find_existing_implicit_branch(NetNet*sig, NetNet*gnd)
{
      Nexus*nex = sig->pin(0).nexus();
      for (Link*cur = nex->first_nlink() ; cur ; cur = cur->next_nlink()) {
	    if (cur->is_equal(sig->pin(0)))
		  continue;

	    if (cur->get_pin() != 0)
		  continue;

	    NetBranch*tmp = dynamic_cast<NetBranch*> (cur->get_obj());
	    if (tmp == 0)
		  continue;

	    if (tmp->name())
		  continue;

	    if (tmp->pin(1).is_linked(gnd->pin(0)))
		  return tmp;
      }

      return 0;
}

NetExpr* elaborate_rval_expr(Design *des, NetScope *scope, ivl_type_t lv_net_type,
			     PExpr *expr, bool need_const, bool force_unsigned)
{
      return elaborate_rval_expr(des, scope, lv_net_type,
				 lv_net_type->base_type(),
				 lv_net_type->packed_width(),
				 expr, need_const, force_unsigned);
}

NetExpr* elaborate_rval_expr(Design*des, NetScope*scope, ivl_type_t lv_net_type,
			     ivl_variable_type_t lv_type, unsigned lv_width,
			     PExpr*expr, bool need_const, bool force_unsigned)
{
      if (debug_elaborate) {
	    cerr << expr->get_fileline() << ": elaborate_rval_expr: "
		 << "expr=" << *expr;
	    if (lv_net_type)
		  cerr << ", lv_net_type=" << *lv_net_type;
	    else
		  cerr << ", lv_net_type=<nil>";

	    cerr << ", lv_type=" << lv_type
		 << ", lv_width=" << lv_width
		 << endl;
      }

      NetExpr *rval;
      int context_wid = -1;
      bool typed_elab = false;

      switch (lv_type) {
	  case IVL_VT_DARRAY:
	  case IVL_VT_QUEUE:
	  case IVL_VT_CLASS:
	      // For these types, use a different elab_and_eval that
	      // uses the lv_net_type. We should eventually transition
	      // all the types to this new form.
	    typed_elab = true;
	    break;
	  case IVL_VT_REAL:
	  case IVL_VT_STRING:
	    break;
	  case IVL_VT_BOOL:
	  case IVL_VT_LOGIC:
            context_wid = lv_width;
	    break;
	  case IVL_VT_VOID:
	  case IVL_VT_NO_TYPE:
	    ivl_assert(*expr, 0);
	    break;
      }

	// If the target is an unpacked array we want full type checking,
	// regardless of the base type of the array.
      if (dynamic_cast<const netuarray_t *>(lv_net_type))
	    typed_elab = true;

	// Special case, PEAssignPattern is context dependend on the type and
	// always uses the typed elaboration
      if (dynamic_cast<PEAssignPattern*>(expr))
	    typed_elab = true;

      if (lv_net_type && typed_elab) {
	    rval = elab_and_eval(des, scope, expr, lv_net_type, need_const);
      } else {
	    rval = elab_and_eval(des, scope, expr, context_wid, need_const,
				 false, lv_type, force_unsigned);
      }

      const netenum_t *lval_enum = dynamic_cast<const netenum_t*>(lv_net_type);
      if (lval_enum) {
	    const netenum_t *rval_enum = rval->enumeration();
	    if (!rval_enum) {
	      cerr << expr->get_fileline() << ": error: "
			      "This assignment requires an explicit cast." << endl;
	      des->errors += 1;
	    } else if (!lval_enum->matches(rval_enum)) {
	      cerr << expr->get_fileline() << ": error: "
			      "Enumeration type mismatch in assignment." << endl;
	      des->errors += 1;
	    }
      }

      return rval;
}

/*
 * If the mode is UPSIZE, make sure the final expression width is at
 * least integer_width, but return the calculated lossless width to
 * the caller.
 */
unsigned PExpr::fix_width_(width_mode_t mode)
{
      unsigned width = expr_width_;
      if ((mode == UPSIZE) && type_is_vectorable(expr_type_)
          && (width < integer_width))
            expr_width_ = integer_width;

      return width;
}

unsigned PExpr::test_width(Design*des, NetScope*, width_mode_t&)
{
      cerr << get_fileline() << ": internal error: I do not know how to"
	   << " test the width of this expression. " << endl;
      cerr << get_fileline() << ":               : Expression is: " << *this
	   << endl;
      des->errors += 1;
      return 1;
}

NetExpr* PExpr::elaborate_expr(Design*des, NetScope*scope, ivl_type_t, unsigned flags) const
{
	// Fall back to the old method. Currently the new method won't be used
	// if the target is a vector type, so we can use an arbitrary width.
      return elaborate_expr(des, scope, 1, flags);
}


NetExpr* PExpr::elaborate_expr(Design*des, NetScope*, unsigned, unsigned) const
{
      cerr << get_fileline() << ": internal error: I do not know how to"
	   << " elaborate this expression. " << endl;
      cerr << get_fileline() << ":               : Expression is: " << *this
	   << endl;
      cerr << get_fileline() << ":               : Expression type: " << typeid(*this).name() << endl;
      des->errors += 1;
      return 0;
}

/*
 * For now, assume that assignment patterns are for dynamic
 * objects. This is not really true as this expression type, fully
 * supported, can assign to packed arrays and structs, unpacked arrays
 * and dynamic arrays.
 */
unsigned PEAssignPattern::test_width(Design*, NetScope*, width_mode_t&)
{
      expr_type_  = IVL_VT_DARRAY;
      expr_width_ = 1;
      min_width_  = 1;
      signed_flag_= false;
      return 1;
}

NetExpr*PEAssignPattern::elaborate_expr(Design*des, NetScope*scope,
					ivl_type_t ntype, unsigned flags) const
{
      bool need_const = NEED_CONST & flags;

      if (auto darray_type = dynamic_cast<const netdarray_t*>(ntype))
	    return elaborate_expr_array_(des, scope, darray_type, need_const, true);

      if (auto uarray_type = dynamic_cast<const netuarray_t*>(ntype)) {
	    return elaborate_expr_uarray_(des, scope, uarray_type,
					  uarray_type->static_dimensions(), 0,
					  need_const);
      }

      if (auto parray_type = dynamic_cast<const netparray_t*>(ntype)) {
	    return elaborate_expr_packed_(des, scope, parray_type->base_type(),
					  parray_type->packed_width(),
					  parray_type->slice_dimensions(), 0,
					  need_const);
      }

      if (auto vector_type = dynamic_cast<const netvector_t*>(ntype)) {
	    return elaborate_expr_packed_(des, scope, vector_type->base_type(),
					  vector_type->packed_width(),
					  vector_type->slice_dimensions(), 0,
					  need_const);
      }

      if (auto struct_type = dynamic_cast<const netstruct_t*>(ntype)) {
	    return elaborate_expr_struct_(des, scope, struct_type,
					  need_const);
      }

      cerr << get_fileline() << ": sorry: I don't know how to elaborate "
	   << "assignment_pattern expressions for " << *ntype << " type yet." << endl;
      cerr << get_fileline() << ":      : Expression is: " << *this
	   << endl;
      des->errors += 1;
      return 0;
}

NetExpr* PEAssignPattern::elaborate_expr_array_(Design *des, NetScope *scope,
					        const netarray_t *array_type,
					        bool need_const, bool up) const
{
	// Special case: If this is an empty pattern (i.e. '{}) then convert
	// this to a null handle. Internally, Icarus Verilog uses this to
	// represent nil dynamic arrays.
      if (parms_.empty()) {
	    NetENull *tmp = new NetENull;
	    tmp->set_line(*this);
	    return tmp;
      }

	// This is an array pattern, so run through the elements of
	// the expression and elaborate each as if they are
	// element_type expressions.
      ivl_type_t elem_type = array_type->element_type();
      vector<NetExpr*> elem_exprs (parms_.size());
      size_t elem_idx = up ? 0 : parms_.size() - 1;
      for (size_t idx = 0 ; idx < parms_.size() ; idx += 1) {
	    elem_exprs[elem_idx] = elaborate_rval_expr(des, scope, elem_type,
						       parms_[idx], need_const);
	    if (up)
		  elem_idx++;
	    else
		  elem_idx--;
      }

      NetEArrayPattern*res = new NetEArrayPattern(array_type, elem_exprs);
      res->set_line(*this);
      return res;
}

NetExpr* PEAssignPattern::elaborate_expr_uarray_(Design *des, NetScope *scope,
						 const netuarray_t *uarray_type,
						 const netranges_t &dims,
						 unsigned int cur_dim,
						 bool need_const) const
{
      if (dims.size() <= cur_dim)
	    return nullptr;

      if (dims[cur_dim].width() != parms_.size()) {
	    cerr << get_fileline() << ": error: Unpacked array assignment pattern expects "
	         << dims[cur_dim].width() << " element(s) in this context.\n"
	         << get_fileline() << ":      : Found "
		 << parms_.size() << " element(s)." << endl;
	    des->errors++;
      }

      bool up = dims[cur_dim].get_msb() < dims[cur_dim].get_lsb();
      if  (cur_dim == dims.size() - 1) {
	    return elaborate_expr_array_(des, scope, uarray_type, need_const, up);
      }

      cur_dim++;
      vector<NetExpr*> elem_exprs(parms_.size());
      size_t elem_idx = up ? 0 : parms_.size() - 1;
      for (size_t idx = 0; idx < parms_.size(); idx++) {
	    NetExpr *expr = nullptr;
	    // Handle nested assignment patterns as a special case. We do not
	    // have a good way of passing the inner dimensions through the
	    // generic elaborate_expr() API and assigment patterns is the only
	    // place where we need it.
	    if (auto ap = dynamic_cast<PEAssignPattern*>(parms_[idx])) {
		  expr = ap->elaborate_expr_uarray_(des, scope, uarray_type,
						    dims, cur_dim, need_const);
	    } else if (dynamic_cast<PEConcat*>(parms_[idx])) {
		  cerr << get_fileline() << ": sorry: "
		       << "Array concatenation is not yet supported."
		       << endl;
		  des->errors++;
	    } else if (dynamic_cast<PEIdent*>(parms_[idx])) {
		  // The only other thing that's allow in this
		  // context is an array slice or identifier.
		  cerr << get_fileline() << ": sorry: "
		       << "Procedural assignment of array or array slice"
		       << " is not yet supported." << endl;
		  des->errors++;
	    } else if (parms_[idx]) {
		  cerr << get_fileline() << ": error: Expression "
		       << *parms_[idx]
		       << " is not compatible with this context."
		       << " Expected array or array-like expression."
		       << endl;
		  des->errors++;
	    }

	    elem_exprs[elem_idx] = expr;

	    if (up)
		  elem_idx++;
	    else
		  elem_idx--;
      }

      NetEArrayPattern *res = new NetEArrayPattern(uarray_type, elem_exprs);
      res->set_line(*this);
      return res;
}

NetExpr* PEAssignPattern::elaborate_expr_packed_(Design *des, NetScope *scope,
						 ivl_variable_type_t base_type,
						 unsigned int width,
						 const netranges_t &dims,
						 unsigned int cur_dim,
						 bool need_const) const
{
      if (dims.size() <= cur_dim) {
	    cerr << get_fileline() << ": error: scalar type is not a valid"
	         << " context for assignment pattern." << endl;
	    des->errors++;
	    return nullptr;
      }

      if (dims[cur_dim].width() != parms_.size()) {
	    cerr << get_fileline() << ": error: Packed array assignment pattern expects "
	         << dims[cur_dim].width() << " element(s) in this context.\n"
	         << get_fileline() << ":      : Found "
		 << parms_.size() << " element(s)." << endl;
	    des->errors++;
      }

      width /= dims[cur_dim].width();
      cur_dim++;

      NetEConcat *concat = new NetEConcat(parms_.size(), 1, base_type);
      for (size_t idx = 0; idx < parms_.size(); idx++) {
	    NetExpr *expr;
	    // Handle nested assignment patterns as a special case. We do not
	    // have a good way of passing the inner dimensions through the
	    // generic elaborate_expr() API and assigment patterns is the only
	    // place where we need it.
	    auto ap = dynamic_cast<PEAssignPattern*>(parms_[idx]);
	    if (ap)
		  expr = ap->elaborate_expr_packed_(des, scope, base_type,
						    width, dims, cur_dim, need_const);
	    else
		  expr = elaborate_rval_expr(des, scope, nullptr,
					     base_type, width,
					     parms_[idx], need_const);
	    if (expr)
		  concat->set(idx, expr);
      }

      return concat;
}

NetExpr* PEAssignPattern::elaborate_expr_struct_(Design *des, NetScope *scope,
						 const netstruct_t *struct_type,
						 bool need_const) const
{
      auto &members = struct_type->members();

      if (members.size() != parms_.size()) {
	    cerr << get_fileline() << ": error: Struct assignment pattern expects "
	         << members.size() << " element(s) in this context.\n"
	         << get_fileline() << ":      : Found "
		 << parms_.size() << " element(s)." << endl;
	    des->errors++;
      }

      NetEConcat *concat = new NetEConcat(parms_.size(), 1,
					  struct_type->base_type());
      for (size_t idx = 0; idx < std::min(parms_.size(), members.size()); idx++) {
	    auto expr = elaborate_rval_expr(des, scope,
					    members[idx].net_type,
					    parms_[idx], need_const);
	    if (expr)
		  concat->set(idx, expr);
      }

      return concat;
}

NetExpr* PEAssignPattern::elaborate_expr(Design*des, NetScope*, unsigned, unsigned) const
{
      cerr << get_fileline() << ": sorry: I do not know how to"
	   << " elaborate assignment patterns using old method." << endl;
      cerr << get_fileline() << ":      : Expression is: " << *this
	   << endl;
      des->errors += 1;
      ivl_assert(*this, 0);
      return 0;
}

unsigned PEBinary::test_width(Design*des, NetScope*scope, width_mode_t&mode)
{
      ivl_assert(*this, left_);
      ivl_assert(*this, right_);

      unsigned r_width = right_->test_width(des, scope, mode);

      width_mode_t saved_mode = mode;

      unsigned l_width = left_->test_width(des, scope, mode);

      if (debug_elaborate) {
	    cerr << get_fileline() << ": PEBinary::test_width: "
		 << "op_=" << op_ << ", l_width=" << l_width
		 << ", r_width=" << r_width
		 << ", saved_mode=" << saved_mode << endl;
      }

        // If the width mode changed, retest the right operand, as it
        // may choose a different width if it is in a lossless context.
      if ((mode >= LOSSLESS) && (saved_mode < LOSSLESS))
	    r_width = right_->test_width(des, scope, mode);

      ivl_variable_type_t l_type =  left_->expr_type();
      ivl_variable_type_t r_type = right_->expr_type();

      if (l_type == IVL_VT_CLASS || r_type == IVL_VT_CLASS) {
	    cerr << get_fileline() << ": error: "
	         << "Class/null is not allowed with the '"
	         << human_readable_op(op_) << "' operator." << endl;
	    des->errors += 1;
      }

      if (l_type == IVL_VT_REAL || r_type == IVL_VT_REAL)
	    expr_type_ = IVL_VT_REAL;
      else if (l_type == IVL_VT_LOGIC || r_type == IVL_VT_LOGIC)
	    expr_type_ = IVL_VT_LOGIC;
      else
	    expr_type_ = IVL_VT_BOOL;

      if (expr_type_ == IVL_VT_REAL) {
            expr_width_  = 1;
            min_width_   = 1;
            signed_flag_ = true;
      } else {
            expr_width_  = max(l_width, r_width);
            min_width_   = max(left_->min_width(), right_->min_width());
            signed_flag_ = left_->has_sign() && right_->has_sign();

              // If the operands are different types, the expression is
              // forced to unsigned. In this case the lossless width
              // calculation is unreliable and we need to make sure the
              // final expression width is at least integer_width.
            if ((mode == LOSSLESS) && (left_->has_sign() != right_->has_sign()))
                  mode = UPSIZE;

            switch (op_) {
                case '+':
                case '-':
                  if (mode >= EXPAND)
                        expr_width_ += 1;
                  break;

                case '*':
                  if (mode >= EXPAND)
                        expr_width_ = l_width + r_width;
                  break;

                case '%':
                case '/':
                  min_width_ = UINT_MAX; // disable width pruning
                  break;

                case 'l': // <<  Should be handled by PEBLeftWidth
                case 'r': // >>  Should be handled by PEBLeftWidth
                case 'R': // >>> Should be handled by PEBLeftWidth
                case '<': // <   Should be handled by PEBComp
                case '>': // >   Should be handled by PEBComp
                case 'e': // ==  Should be handled by PEBComp
                case 'E': // === Should be handled by PEBComp
                case 'w': // ==? Should be handled by PEBComp
                case 'L': // <=  Should be handled by PEBComp
                case 'G': // >=  Should be handled by PEBComp
                case 'n': // !=  Should be handled by PEBComp
                case 'N': // !== Should be handled by PEBComp
                case 'W': // !=? Should be handled by PEBComp
                case 'p': // **  should be handled by PEBLeftWidth
                  ivl_assert(*this, 0);
                default:
                  break;
            }
      }

      return fix_width_(mode);
}

/*
 * Elaborate binary expressions. This involves elaborating the left
 * and right sides, and creating one of a variety of different NetExpr
 * types.
 */
NetExpr* PEBinary::elaborate_expr(Design*des, NetScope*scope,
				  unsigned expr_wid, unsigned flags) const
{
      flags &= ~SYS_TASK_ARG; // don't propagate the SYS_TASK_ARG flag

      ivl_assert(*this, left_);
      ivl_assert(*this, right_);

	// Handle the special case that one of the operands is a real
	// value and the other is a vector type. In that case,
	// elaborate the vectorable argument as self-determined.
        // Propagate the expression type (signed/unsigned) down to
        // any context-determined operands.
      unsigned l_width = expr_wid;
      unsigned r_width = expr_wid;
      if (left_->expr_type()==IVL_VT_REAL
	  && type_is_vectorable(right_->expr_type())) {
	    r_width = right_->expr_width();
      } else {
            right_->cast_signed(signed_flag_);
      }
      if (right_->expr_type()==IVL_VT_REAL
	  && type_is_vectorable(left_->expr_type())) {
	    l_width = left_->expr_width();
      } else {
            left_->cast_signed(signed_flag_);
      }

      NetExpr*lp =  left_->elaborate_expr(des, scope, l_width, flags);
      NetExpr*rp = right_->elaborate_expr(des, scope, r_width, flags);
      if ((lp == 0) || (rp == 0)) {
	    delete lp;
	    delete rp;
	    return 0;
      }

      return elaborate_expr_base_(des, lp, rp, expr_wid);
}

/*
 * This is the common elaboration of the operator. It presumes that the
 * operands are elaborated as necessary, and all I need to do is make
 * the correct NetEBinary object and connect the parameters.
 */
NetExpr* PEBinary::elaborate_expr_base_(Design*des,
					NetExpr*lp, NetExpr*rp,
					unsigned expr_wid) const
{
      if (debug_elaborate) {
	    cerr << get_fileline() << ": debug: elaborate expression "
		 << *this << " expr_width=" << expr_wid << endl;
      }

      NetExpr*tmp;

      switch (op_) {
	  default:
	    tmp = new NetEBinary(op_, lp, rp, expr_wid, signed_flag_);
	    tmp->set_line(*this);
	    break;

	  case 'a':
	  case 'o':
	  case 'q':
	  case 'Q':
	    cerr << get_fileline() << ": internal error: "
		 << "Elaboration of " << human_readable_op(op_)
		 << " Should have been handled in NetEBLogic::elaborate."
		 << endl;
	    des->errors += 1;
	    return 0;

	  case 'p':
	    cerr << get_fileline() << ": internal error: "
		 << "Elaboration of " << human_readable_op(op_)
		 << " Should have been handled in NetEBPower::elaborate."
		 << endl;
	    des->errors += 1;
	    return 0;

	  case '*':
	    tmp = elaborate_expr_base_mult_(des, lp, rp, expr_wid);
	    break;

	  case '%':
	  case '/':
	    tmp = elaborate_expr_base_div_(des, lp, rp, expr_wid);
	    break;

	  case 'l':
	  case 'r':
	  case 'R':
	    cerr << get_fileline() << ": internal error: "
		 << "Elaboration of " << human_readable_op(op_)
		 << " Should have been handled in NetEBShift::elaborate."
		 << endl;
	    des->errors += 1;
	    return 0;

	  case '^':
	  case '&':
	  case '|':
	  case 'O': // NOR (~|)
	  case 'A': // NAND (~&)
	  case 'X':
	    tmp = elaborate_expr_base_bits_(des, lp, rp, expr_wid);
	    break;

	  case '+':
	  case '-':
	    tmp = new NetEBAdd(op_, lp, rp, expr_wid, signed_flag_);
	    tmp->set_line(*this);
	    break;

	  case 'E': /* === */
	  case 'N': /* !== */
	  case 'e': /* == */
	  case 'n': /* != */
	  case 'L': /* <= */
	  case 'G': /* >= */
	  case '<':
	  case '>':
	    cerr << get_fileline() << ": internal error: "
		 << "Elaboration of " << human_readable_op(op_)
		 << " Should have been handled in NetEBComp::elaborate."
		 << endl;
	    des->errors += 1;
	    return 0;

	  case 'm': // min(l,r)
	  case 'M': // max(l,r)
	    tmp = new NetEBMinMax(op_, lp, rp, expr_wid, signed_flag_);
	    tmp->set_line(*this);
	    break;
      }

      return tmp;
}

NetExpr* PEBinary::elaborate_expr_base_bits_(Design*des,
					     NetExpr*lp, NetExpr*rp,
					     unsigned expr_wid) const
{
      if (lp->expr_type() == IVL_VT_REAL || rp->expr_type() == IVL_VT_REAL) {
	    cerr << get_fileline() << ": error: "
	         << human_readable_op(op_)
	         << " operator may not have REAL operands." << endl;
	    des->errors += 1;
	    return 0;
      }

      NetEBBits*tmp = new NetEBBits(op_, lp, rp, expr_wid, signed_flag_);
      tmp->set_line(*this);

      return tmp;
}

NetExpr* PEBinary::elaborate_expr_base_div_(Design*des,
					    NetExpr*lp, NetExpr*rp,
					    unsigned expr_wid) const
{
	/* The % operator does not support real arguments in
	   baseline Verilog. But we allow it in our extended
	   form of Verilog. */
      if (op_ == '%' && ! gn_icarus_misc_flag) {
	    if (lp->expr_type() == IVL_VT_REAL ||
		rp->expr_type() == IVL_VT_REAL) {
		  cerr << get_fileline() << ": error: Modulus operator "
			"may not have REAL operands." << endl;
		  des->errors += 1;
	    }
      }

      NetEBDiv*tmp = new NetEBDiv(op_, lp, rp, expr_wid, signed_flag_);
      tmp->set_line(*this);

      return tmp;
}

NetExpr* PEBinary::elaborate_expr_base_mult_(Design*,
					     NetExpr*lp, NetExpr*rp,
					     unsigned expr_wid) const
{
	// Keep constants on the right side.
      if (dynamic_cast<NetEConst*>(lp)) {
	    NetExpr*tmp = lp;
	    lp = rp;
	    rp = tmp;
      }

	// Handle a few special case multiplies against constants.
      if (NetEConst*rp_const = dynamic_cast<NetEConst*> (rp)) {
	    verinum rp_val = rp_const->value();

	    if (!rp_val.is_defined() && (lp->expr_type() == IVL_VT_LOGIC)) {
		  NetEConst*tmp = make_const_x(expr_wid);
                  tmp->cast_signed(signed_flag_);
                  tmp->set_line(*this);

		  return tmp;
	    }

	    if (rp_val.is_zero() && (lp->expr_type() == IVL_VT_BOOL)) {
		  NetEConst*tmp = make_const_0(expr_wid);
                  tmp->cast_signed(signed_flag_);
                  tmp->set_line(*this);

		  return tmp;
	    }
      }

      NetEBMult*tmp = new NetEBMult(op_, lp, rp, expr_wid, signed_flag_);
      tmp->set_line(*this);

      return tmp;
}

unsigned PEBComp::test_width(Design*des, NetScope*scope, width_mode_t&)
{
      ivl_assert(*this, left_);
      ivl_assert(*this, right_);

	// The width and type of a comparison are fixed and well known.
      expr_type_   = IVL_VT_LOGIC;
      expr_width_  = 1;
      min_width_   = 1;
      signed_flag_ = false;

	// The widths of the operands are semi-self-determined. They
        // affect each other, but not the result.
      width_mode_t mode = SIZED;

      unsigned r_width = right_->test_width(des, scope, mode);

      width_mode_t saved_mode = mode;

      unsigned l_width = left_->test_width(des, scope, mode);

        // If the width mode changed, retest the right operand, as it
        // may choose a different width if it is in a lossless context.
      if ((mode >= LOSSLESS) && (saved_mode < LOSSLESS))
	    r_width = right_->test_width(des, scope, mode);

      ivl_variable_type_t l_type =  left_->expr_type();
      ivl_variable_type_t r_type = right_->expr_type();

      l_width_ = l_width;
      if (type_is_vectorable(l_type) && (r_width > l_width))
	    l_width_ = r_width;

      r_width_ = r_width;
      if (type_is_vectorable(r_type) && (l_width > r_width))
	    r_width_ = l_width;

	// If the expression is lossless and smaller than the integer
	// minimum, then tweak the size up.
	// NOTE: I really would rather try to figure out what it would
	// take to get expand the sub-expressions so that they are
	// exactly the right width to behave just like infinite
	// width. I suspect that adding 1 more is sufficient in all
	// cases, but I'm not certain. Ideas?
      if (mode >= EXPAND) {
            if (type_is_vectorable(l_type) && (l_width_ < integer_width))
	          l_width_ += 1;
            if (type_is_vectorable(r_type) && (r_width_ < integer_width))
	          r_width_ += 1;
      }

      if (debug_elaborate) {
	    cerr << get_fileline() << ": PEBComp::test_width: "
		 << "Comparison expression operands are "
		 << l_type << " " << l_width << " bits and "
		 << r_type << " " << r_width << " bits. Resorting to "
		 << l_width_ << " bits and "
		 << r_width_ << " bits." << endl;
      }

      switch (op_) {
	case 'e': /* == */
	case 'n': /* != */
	case 'E': /* === */
	case 'N': /* !== */
	    if ((l_type == IVL_VT_CLASS || r_type == IVL_VT_CLASS) &&
	        l_type != r_type) {
		  cerr << get_fileline() << ": error: "
		       << "Both arguments ("<< l_type << ", " << r_type
		       << ") must be class/null for '"
		       << human_readable_op(op_) << "' operator." << endl;
		  des->errors += 1;
	    }
	    break;
	default:
	    if (l_type == IVL_VT_CLASS || r_type == IVL_VT_CLASS) {
		  cerr << get_fileline() << ": error: "
		       << "Class/null is not allowed with the '"
		       << human_readable_op(op_) << "' operator." << endl;
		  des->errors += 1;
	    }
      }


      return expr_width_;
}

NetExpr* PEBComp::elaborate_expr(Design*des, NetScope*scope,
				 unsigned expr_wid, unsigned flags) const
{
      flags &= ~SYS_TASK_ARG; // don't propagate the SYS_TASK_ARG flag

      ivl_assert(*this, left_);
      ivl_assert(*this, right_);

      if (debug_elaborate) {
	    cerr << get_fileline() << ": PEBComp::elaborate_expr: "
		 << "Left expression: " << *left_ << endl;
	    cerr << get_fileline() << ": PEBComp::elaborate_expr: "
		 << "Right expression: " << *right_ << endl;
	    cerr << get_fileline() << ": PEBComp::elaborate_expr: "
		 << "op_: " << human_readable_op(op_)
		 << ", expr_wid=" << expr_wid
		 << ", flags=0x" << hex << flags << dec << endl;
      }

        // Propagate the comparison type (signed/unsigned) down to
        // the operands.
      if (type_is_vectorable(left_->expr_type()) && !left_->has_sign())
	    right_->cast_signed(false);
      if (type_is_vectorable(right_->expr_type()) && !right_->has_sign())
	    left_->cast_signed(false);

      NetExpr*lp =  left_->elaborate_expr(des, scope, l_width_, flags);
      if (lp && debug_elaborate) {
	    cerr << get_fileline() << ": PEBComp::elaborate_expr: "
		 << "Elaborated left_: " << *lp << endl;
      }
      NetExpr*rp = right_->elaborate_expr(des, scope, r_width_, flags);
      if (rp && debug_elaborate) {
	    cerr << get_fileline() << ": PEBComp::elaborate_expr: "
		 << "Elaborated right_: " << *rp << endl;
      }

      if ((lp == 0) || (rp == 0)) {
	    delete lp;
	    delete rp;
	    return 0;
      }

      eval_expr(lp, l_width_);
      eval_expr(rp, r_width_);

	// Handle some operand-specific special cases...
      switch (op_) {
	  case 'E': /* === */
	  case 'N': /* !== */
	    if (lp->expr_type() == IVL_VT_REAL ||
		lp->expr_type() == IVL_VT_STRING ||
		rp->expr_type() == IVL_VT_REAL ||
		rp->expr_type() == IVL_VT_STRING) {
		  cerr << get_fileline() << ": error: "
		       << human_readable_op(op_)
		       << " operator may not have REAL or STRING operands."
		       << endl;
		  des->errors += 1;
		  return 0;
	    }
	    break;
	  case 'w': /* ==? */
	  case 'W': /* !=? */
	    if ((lp->expr_type() != IVL_VT_BOOL && lp->expr_type() != IVL_VT_LOGIC) ||
		(rp->expr_type() != IVL_VT_BOOL && rp->expr_type() != IVL_VT_LOGIC)) {
		  cerr << get_fileline() << ": error: "
		       << human_readable_op(op_)
		       << " operator may only have INTEGRAL operands."
		       << endl;
		  des->errors += 1;
		  return 0;
	    }
	    break;
	  default:
	    break;
      }

      NetExpr*tmp = new NetEBComp(op_, lp, rp);
      tmp->set_line(*this);

      return pad_to_width(tmp, expr_wid, signed_flag_, *this);
}

unsigned PEBLogic::test_width(Design*, NetScope*, width_mode_t&)
{
	// The width and type of a logical operation are fixed.
      expr_type_   = IVL_VT_LOGIC;
      expr_width_  = 1;
      min_width_   = 1;
      signed_flag_ = false;

        // The widths of the operands are self determined. We don't need
        // them now, so they can be tested when they are elaborated.

      return expr_width_;
}

NetExpr*PEBLogic::elaborate_expr(Design*des, NetScope*scope,
				 unsigned expr_wid, unsigned flags) const
{
      ivl_assert(*this, left_);
      ivl_assert(*this, right_);

      bool need_const = NEED_CONST & flags;
      NetExpr*lp = elab_and_eval(des, scope,  left_, -1, need_const);
      NetExpr*rp = elab_and_eval(des, scope, right_, -1, need_const);
      if ((lp == 0) || (rp == 0)) {
	    delete lp;
	    delete rp;
	    return 0;
      }

      lp = condition_reduce(lp);
      rp = condition_reduce(rp);

      NetExpr*tmp = new NetEBLogic(op_, lp, rp);
      tmp->set_line(*this);

      return pad_to_width(tmp, expr_wid, signed_flag_, *this);
}

unsigned PEBLeftWidth::test_width(Design*des, NetScope*scope, width_mode_t&mode)
{
      ivl_assert(*this, left_);
      ivl_assert(*this, right_);

      if (debug_elaborate) {
	    cerr << get_fileline() << ": PEBLeftWidth::test_width: "
		 << "op_=" << op_
		 << ", left_=" << *left_
		 << ", right_=" << *right_
		 << ", mode=" << width_mode_name(mode) << endl;
      }

        // The right operand is self determined. Test its type and
        // width for use later. We only need to know its width now
        // if the left operand is unsized and we need to calculate
        // the lossless width.
      width_mode_t r_mode = SIZED;
      unsigned r_width = right_->test_width(des, scope, r_mode);

	// The left operand is what will determine the size of the
	// expression. The l_mode will be converted to UNSIZED if the
	// expression does not have a well-determined size.
      width_mode_t l_mode = SIZED;
      expr_width_  = left_->test_width(des, scope, l_mode);
      expr_type_   = left_->expr_type();
      signed_flag_ = left_->has_sign();

      if (expr_type_ == IVL_VT_CLASS || right_->expr_type() == IVL_VT_CLASS) {
	    cerr << get_fileline() << ": error: "
	         << "Class/null is not allowed with the '"
	         << human_readable_op(op_) << "' operator." << endl;
	    des->errors += 1;
      }

      if (mode==SIZED)
	    mode = l_mode;

	// The left operand width defines the size of the
	// expression. If the expression has a well-defined size, the
	// left_->test_width() above would have set mode==SIZED and we
	// can skip a lot of stuff. But if the mode is an undetermined
	// size, we need to figure out what we really want to keep a
	// lossless value. That's what the following if(...) {...} is
	// all about.
      if ((mode >= EXPAND) && type_is_vectorable(expr_type_)) {

              // We need to make our best guess at the right operand
              // value, to minimize the calculated width. This is
              // particularly important for the power operator...

              // Start off by assuming the maximum value for the
              // type and width of the right operand.
            long r_val = LONG_MAX;
            if (r_width < sizeof(long)*8) {
                  r_val = (1UL << r_width) - 1UL;
                  if ((op_ == 'p') && right_->has_sign())
                        r_val >>= 1;
            }

              // If the right operand is constant, we can use the
              // actual value.
            NetExpr*rp = right_->elaborate_expr(des, scope, r_width, NO_FLAGS);
            if (rp) {
                  eval_expr(rp, r_width);
            } else {
                  // error recovery
                  PEVoid*tmp = new PEVoid();
                  tmp->set_line(*this);
                  delete right_;
                  right_ = tmp;
            }
            NetEConst*rc = dynamic_cast<NetEConst*> (rp);
	      // Adjust the expression width that can be converter depending
	      // on if the R-value is signed or not.
	    unsigned c_width = sizeof(long)*8;
	    if (! right_->has_sign()) c_width -= 1;
	    if (rc && (r_width <= c_width)) r_val = rc->value().as_long();

	    if (debug_elaborate && rc) {
		  cerr << get_fileline() << ": PEBLeftWidth::test_width: "
		       << "Evaluated rc=" << *rc
		       << ", r_val=" << r_val
		       << ", width_cap=" << width_cap << endl;
	    }

              // Clip to a sensible range to avoid underflow/overflow
              // in the following calculations.
            if (r_val < 0)
                  r_val = 0;
            if ((unsigned long)r_val > width_cap)
                  r_val = width_cap;

              // If the left operand is a simple unsized number, we
              // can calculate the actual width required for the power
              // operator.
            PENumber*lc = dynamic_cast<PENumber*> (left_);

              // Now calculate the lossless width.
            unsigned use_width = expr_width_;
            switch (op_) {
                case 'l': // <<
		  if (l_mode != SIZED)
			use_width += (unsigned)r_val;
                  break;

                case 'r': // >>
                case 'R': // >>>
                    // A logical shift will effectively coerce a signed
                    // operand to unsigned. We have to assume an arithmetic
                    // shift may do the same, as we don't yet know the final
                    // expression type.
                  if ((mode == LOSSLESS) && signed_flag_)
                        mode = UPSIZE;
                  break;

                case 'p': // **
                  if (lc && rc) {
                        verinum result = pow(lc->value(), rc->value());
                        use_width = max(use_width, result.len());
                  } else {
                        if (signed_flag_) use_width -= 1;
                        use_width *= (unsigned)r_val;
                        if (signed_flag_) use_width += 2;
                  }
                  break;

                default:
                  cerr << get_fileline() << ": internal error: "
                       << "Unexpected opcode " << human_readable_op(op_)
                       << " in PEBLeftWidth::test_width." << endl;
                  des->errors += 1;
            }

              // If the right operand is not constant, we could end up
              // grossly overestimating the required width. So in this
              // case, don't expand beyond the width of an integer
              // (which meets the requirements of the standard).
            if ((rc == 0) && (use_width > expr_width_) && (use_width > integer_width))
                  use_width = integer_width;

	    if (use_width >= width_cap) {
		  cerr << get_fileline() << ": warning: "
		       << "Unsized expression (" << *this << ")"
		       << " expanded beyond and was clipped to " << use_width
		       << " bits. Try using sized operands." << endl;
	    }
            expr_width_ = use_width;
      }

      if (op_ == 'l')
            min_width_ = left_->min_width();
      else
            min_width_ = UINT_MAX; // disable width pruning

      if (debug_elaborate) {
	    cerr << get_fileline() << ": PEBLeftWidth::test_width: "
		 << "Done calculating expr_width_=" << expr_width_
		 << ", min_width_=" << min_width_
		 << ", mode=" << width_mode_name(mode) << endl;
      }

      return fix_width_(mode);
}

NetExpr*PEBLeftWidth::elaborate_expr(Design*des, NetScope*scope,
				     unsigned expr_wid, unsigned flags) const
{
      flags &= ~SYS_TASK_ARG; // don't propagate the SYS_TASK_ARG flag

      ivl_assert(*this, left_);

        // The left operand is always context determined, so propagate
        // down the expression type (signed/unsigned).
      left_->cast_signed(signed_flag_);

      unsigned r_width = right_->expr_width();

      NetExpr*lp =  left_->elaborate_expr(des, scope, expr_wid, flags);
      NetExpr*rp = right_->elaborate_expr(des, scope, r_width,  flags);
      if (lp == 0 || rp == 0) {
	    delete lp;
	    delete rp;
	    return 0;
      }

        // For shift operations, the right operand is always treated as
        // unsigned, so coerce it if necessary.
      if ((op_ != 'p') && rp->has_sign()) {
            rp = new NetESelect(rp, 0, rp->expr_width());
            rp->cast_signed(false);
            rp->set_line(*this);
      }

      eval_expr(lp, expr_wid);
      eval_expr(rp, r_width);

      return elaborate_expr_leaf(des, lp, rp, expr_wid);
}

NetExpr*PEBPower::elaborate_expr_leaf(Design*, NetExpr*lp, NetExpr*rp,
				      unsigned expr_wid) const
{
      if (debug_elaborate) {
	    cerr << get_fileline() << ": debug: elaborate expression "
		 << *this << " expr_wid=" << expr_wid << endl;
      }

      NetExpr*tmp = new NetEBPow(op_, lp, rp, expr_wid, signed_flag_);
      tmp->set_line(*this);

      return tmp;
}

static unsigned int sign_cast_width(Design*des, NetScope*scope, PExpr &expr,
				    PExpr::width_mode_t&mode)
{
      unsigned int width;

      // The argument type/width is self-determined, but affects
      // the result width.
      PExpr::width_mode_t arg_mode = PExpr::SIZED;
      width = expr.test_width(des, scope, arg_mode);

      if ((arg_mode >= PExpr::EXPAND) && type_is_vectorable(expr.expr_type())) {
	    if (mode < PExpr::LOSSLESS)
		  mode = PExpr::LOSSLESS;
	    if (width < integer_width)
		  width = integer_width;
     }

     return width;
}

NetExpr*PEBShift::elaborate_expr_leaf(Design*des, NetExpr*lp, NetExpr*rp,
				      unsigned expr_wid) const
{
      switch (op_) {
	  case 'l': // <<
	  case 'r': // >>
	  case 'R': // >>>
	    break;

	  default:
	    cerr << get_fileline() << ": internal error: "
		 << "Unexpected opcode " << human_readable_op(op_)
		 << " in PEBShift::elaborate_expr_leaf." << endl;
	    des->errors += 1;
            return 0;
      }

      if (lp->expr_type() == IVL_VT_REAL || rp->expr_type() == IVL_VT_REAL) {
	    cerr << get_fileline() << ": error: "
	         << human_readable_op(op_)
	         << " operator may not have REAL operands." << endl;
	    des->errors += 1;
            delete lp;
            delete rp;
	    return 0;
      }

      NetExpr*tmp;

	// If the left expression is constant, then there are some
	// special cases we can work with. If the left expression is
	// not constant, but the right expression is constant, then
	// there are some other interesting cases. But if neither are
	// constant, then there is the general case.

      if (NetEConst*lpc = dynamic_cast<NetEConst*> (lp)) {

	      // Special case: The left expression is zero. If the
	      // shift value contains no 'x' or 'z' bits, the result
	      // is going to be zero.
	    if (lpc->value().is_defined() && lpc->value().is_zero()
		&& (rp->expr_type() == IVL_VT_BOOL)) {

		  if (debug_elaborate)
			cerr << get_fileline() << ": debug: "
			     << "Shift of zero always returns zero."
			     << " Elaborate as constant zero." << endl;

		  tmp = make_const_0(expr_wid);
                  tmp->cast_signed(signed_flag_);
                  tmp->set_line(*this);

                  return tmp;
            }

      } else if (NetEConst*rpc = dynamic_cast<NetEConst*> (rp)) {

              // Special case: The shift value contains 'x' or 'z' bits.
              // Elaborate as a constant-x.
            if (!rpc->value().is_defined()) {

		  if (debug_elaborate)
			cerr << get_fileline() << ": debug: "
			     << "Shift by undefined value. "
			     << "Elaborate as constant 'x'." << endl;

		  tmp = make_const_x(expr_wid);
                  tmp->cast_signed(signed_flag_);
                  tmp->set_line(*this);

                  delete lp;
                  delete rp;
                  return tmp;
	    }

	    unsigned long shift = rpc->value().as_ulong();

              // Special case: The shift is zero. The result is simply
              // the left operand.
	    if (shift == 0) {

		  if (debug_elaborate)
			cerr << get_fileline() << ": debug: "
			     << "Shift by zero. Elaborate as the "
			     << "left hand operand." << endl;

                  delete rp;
                  return lp;
	    }

	      // Special case: the shift is at least the size of the entire
	      // left operand, and the shift is a signed right shift.
              // Elaborate as a replication of the top bit of the left
              // expression.
	    if ((op_=='R' && signed_flag_) && (shift >= expr_wid)) {

		  if (debug_elaborate)
			cerr << get_fileline() << ": debug: "
			     << "Value signed-right-shifted " << shift
			     << " beyond width of " << expr_wid
			     << ". Elaborate as replicated top bit." << endl;

		  tmp = new NetEConst(verinum(expr_wid-1));
		  tmp->set_line(*this);
		  tmp = new NetESelect(lp, tmp, 1);
		  tmp->set_line(*this);
		  tmp = pad_to_width(tmp, expr_wid, true, *this);

                  delete rp;
		  return tmp;
	    }

	      // Special case: The shift is at least the size of the entire
	      // left operand, and the shift is not a signed right shift
              // (which is caught by the previous special case). Elaborate
              // as a constant-0.
	    if (shift >= expr_wid) {

		  if (debug_elaborate)
			cerr << get_fileline() << ": debug: "
			     << "Value shifted " << shift
			     << " beyond width of " << expr_wid
			     << ". Elaborate as constant zero." << endl;

		  tmp = make_const_0(expr_wid);
                  tmp->cast_signed(signed_flag_);
		  tmp->set_line(*this);

                  delete lp;
                  delete rp;
		  return tmp;
	    }
      }

	// Fallback, handle the general case.
      tmp = new NetEBShift(op_, lp, rp, expr_wid, signed_flag_);
      tmp->set_line(*this);

      return tmp;
}

unsigned PECallFunction::test_width_sfunc_(Design*des, NetScope*scope,
                                           width_mode_t&mode)
{
      perm_string name = peek_tail_name(path_);

      if (name=="$ivlh_to_unsigned") {
	    ivl_assert(*this, parms_.size() == 2);
	      // The Icarus Verilog specific $ivlh_to_unsigned() system
	      // task takes a second argument which is the output
	      // size. This can be an arbitrary constant function.
	    PExpr *pexpr = parms_[1].parm;
	    if (pexpr == 0) {
		  cerr << get_fileline() << ": error: "
		       << "Missing $ivlh_to_unsigned width." << endl;
		  return 0;
	    }

	    NetExpr*nexpr = elab_and_eval(des, scope, pexpr, -1, true);
	    if (nexpr == 0) {
		  cerr << get_fileline() << ": error: "
		       << "Unable to evaluate " << name
		       << " width argument: " << *pexpr << endl;
		  return 0;
	    }

	    long value = 0;
	    bool rc = eval_as_long(value, nexpr);
	    ivl_assert(*this, rc && value>=0);

	      // The argument width is self-determined and doesn't
	      // affect the result width.
	    width_mode_t arg_mode = SIZED;
	    parms_[0].parm->test_width(des, scope, arg_mode);

	    expr_type_  = pexpr->expr_type();
	    expr_width_ = value;
	    min_width_  = value;
	    signed_flag_= false;
	    return expr_width_;
      }

      if (name=="$signed" || name=="$unsigned") {
	    PExpr *expr = parms_[0].parm;
	    if (expr == 0)
		  return 0;

	    expr_width_  = sign_cast_width(des, scope, *expr, mode);
	    expr_type_   = expr->expr_type();
            min_width_   = expr->min_width();
            signed_flag_ = (name[1] == 's');

	    if (debug_elaborate)
		  cerr << get_fileline() << ": debug: " << name
		       << " argument width = " << expr_width_ << "." << endl;

            return expr_width_;
      }

      if (name=="$sizeof" || name=="$bits") {
	    PExpr *expr = parms_[0].parm;
	    if (expr == 0)
		  return 0;

	    if (! dynamic_cast<PETypename*>(expr)) {
		    // The argument type/width is self-determined and doesn't
		    // affect the result type/width. Note that if the
		    // argument is a type name (a special case) then
		    // don't bother with this step.
		  width_mode_t arg_mode = SIZED;
		  expr->test_width(des, scope, arg_mode);
	    }

	    expr_type_   = IVL_VT_LOGIC;
	    expr_width_  = integer_width;
	    min_width_   = integer_width;
            signed_flag_ = true;

	    if (debug_elaborate)
		  cerr << get_fileline() << ": " << __func__ << ": "
		       << "test_width of " << name << " returns test_width"
		       << " of compiler integer." << endl;

	    return expr_width_;
      }

      if (name=="$is_signed") {
	    PExpr *expr = parms_[0].parm;
	    if (expr == 0)
		  return 0;

              // The argument type/width is self-determined and doesn't
              // affect the result type/width.
            width_mode_t arg_mode = SIZED;
	    expr->test_width(des, scope, arg_mode);

	    expr_type_   = IVL_VT_BOOL;
	    expr_width_  = 1;
	    min_width_   = 1;
            signed_flag_ = false;

	    if (debug_elaborate)
		  cerr << get_fileline() << ": " << __func__ << ": "
		       << "test_width of $is_signed returns test_width"
		       << " of 1." << endl;

	    return expr_width_;
      }

	/* Get the return type of the system function by looking it up
	   in the sfunc_table. */
      const struct sfunc_return_type*sfunc_info = lookup_sys_func(name);

      expr_type_   = sfunc_info->type;
      expr_width_  = sfunc_info->wid;
      min_width_   = expr_width_;
      signed_flag_ = sfunc_info->signed_flag;

      is_overridden_ = sfunc_info->override_flag;

      if (debug_elaborate)
	    cerr << get_fileline() << ": " << __func__ << ": "
		 << "test_width of system function " << name
		 << " returns wid=" << expr_width_
		 << ", type=" << expr_type_ << "." << endl;

      return expr_width_;
}

/*
 * Get the function definition from the scope that we believe to be a
 * function. If it is not, return 0. If it is, handle the special case that we
 * may be still elaborating things. For example:
 *
 *    localparam foo = func(...)
 *
 * In this case, the function is not necessarily elaborated yet, and we need
 * to force enough elaboration that we can get a definition.
 */
static NetFuncDef* find_function_definition(Design*des, NetScope*,
					    NetScope*func)
{
      if (func && (func->type() == NetScope::FUNC)) {
	    if (func->elab_stage() < 2) {
		  func->need_const_func(true);
		  const PFunction*pfunc = func->func_pform();
		  ivl_assert(*func, pfunc);
		  pfunc->elaborate_sig(des, func);
	    }
	    return func->func_def();
      }
      return 0;
}

unsigned PECallFunction::test_width_method_(Design*, NetScope*,
					    symbol_search_results&search_results,
					    width_mode_t&)
{
      if (!gn_system_verilog())
	    return 0;

      if (debug_elaborate) {
	    cerr << get_fileline() << ": PECallFunction::test_width_method_: "
		 << "search_results.path_head: " << search_results.path_head << endl;
	    cerr << get_fileline() << ": PECallFunction::test_width_method_: "
		 << "search_results.path_tail: " << search_results.path_tail << endl;
	    if (search_results.net)
		  cerr << get_fileline() << ": PECallFunction::test_width_method_: "
		       << "search_results.net->data_type: " << search_results.net->data_type() << endl;
	    if (search_results.net && search_results.net->net_type())
		  cerr << get_fileline() << ": PECallFunction::test_width_method_: "
		       << "search_results.net->net_type: " << *search_results.net->net_type() << endl;
      }

      // Don't support multiple chained methods yet.
      if (search_results.path_tail.size() > 1) {
	    if (debug_elaborate) {
		  cerr << get_fileline() << ": PECallFunction::test_width_method_: "
		       << "Chained path tail (" << search_results.path_tail
		       << ") not supported." << endl;
	    }
	    return 0;
      }

      ivl_assert(*this, search_results.path_tail.size() == 1);
      perm_string method_name = search_results.path_tail.back().name;

      // Dynamic array variable without a select expression. The method
      // applies to the array itself, and not to the object that might be
      // indexed from it. So return
      // the expr_width for the return value of the queue method. For example:
      //    <scope>.x.size();
      // In this example, x is a dynamic array.
      if (search_results.net && search_results.net->data_type()==IVL_VT_DARRAY
	  && search_results.path_head.back().index.empty()) {

	    NetNet*net = search_results.net;
	    const netdarray_t*darray = net->darray_type();
	    ivl_assert(*this, darray);

	    if (method_name == "size") {
		  expr_type_  = IVL_VT_BOOL;
		  expr_width_ = 32;
		  min_width_  = expr_width_;
		  signed_flag_= true;
		  return expr_width_;
	    }

	    return 0;
      }

      // Queue variable without a select expression. The method applies to the
      // queue, and not to the object that might be indexed from it. So return
      // the expr_width for the return value of the queue method. For example:
      //    <scope>.x.size();
      // In this example, x is a queue.
      if (search_results.net && search_results.net->data_type()==IVL_VT_QUEUE
	  && search_results.path_head.back().index.empty()) {

	    NetNet*net = search_results.net;
	    const netdarray_t*darray = net->darray_type();
	    ivl_assert(*this, darray);

	    if (method_name == "size") {
		  expr_type_  = IVL_VT_BOOL;
		  expr_width_ = 32;
		  min_width_  = expr_width_;
		  signed_flag_= true;
		  return expr_width_;
	    }

	    if (method_name=="pop_back" || method_name=="pop_front") {
		  expr_type_  = darray->element_base_type();
		  expr_width_ = darray->element_width();
		  min_width_  = expr_width_;
		  signed_flag_= darray->get_signed();
		  return expr_width_;
	    }

	    return 0;
      }

      // Queue variable with a select expression. The type of this expression
      // is the type of the object that will interpret the method. For
      // example:
      //    <scope>.x[e].len()
      // If for example x is a queue of strings, then x[e] is a string and
      // x[e].len() is the length of the string.
      if (search_results.net
	  && (search_results.net->data_type()==IVL_VT_QUEUE || search_results.net->data_type()==IVL_VT_DARRAY)
	  && search_results.path_head.back().index.size()) {

	    NetNet*net = search_results.net;
	    const netdarray_t*darray = net->darray_type();
	    ivl_assert(*this, darray);

	    if (darray->element_base_type()==IVL_VT_STRING && method_name=="atohex") {
		  expr_type_  = IVL_VT_BOOL;
		  expr_width_ = integer_width;
		  min_width_  = integer_width;
		  signed_flag_ = true;
		  return expr_width_;
	    }

	    if (darray->element_base_type()==IVL_VT_STRING && method_name=="atoi") {
		  expr_type_  = IVL_VT_BOOL;
		  expr_width_ = integer_width;
		  min_width_  = integer_width;
		  return expr_width_;
	    }

	    if (darray->element_base_type()==IVL_VT_STRING && method_name=="len") {
		  expr_type_  = IVL_VT_BOOL;
		  expr_width_ = 32;
		  min_width_  = 32;
		  signed_flag_= true;
		  return expr_width_;
	    }
      }

      // Enumeration variable. Check for the various enumeration methods.
      if (search_results.net && search_results.net->enumeration()) {
	    NetNet*net = search_results.net;
	    const netenum_t*enum_type = net->enumeration();

	    if (method_name=="first" || method_name=="last"
		|| method_name=="prev" || method_name=="next") {
		  expr_type_  = IVL_VT_BOOL;
		  expr_width_ = enum_type->packed_width();
		  min_width_  = expr_width_;
		  signed_flag_= enum_type->get_signed();
		  return expr_width_;
	    }
	    if (method_name=="num") {
		  expr_type_  = IVL_VT_BOOL;
		  expr_width_ = 32;
		  min_width_  = expr_width_;
		  signed_flag_= true;
		  return expr_width_;
	    }
	    if (method_name=="name") {
		  expr_type_  = IVL_VT_STRING;
		  expr_width_ = 1;
		  min_width_  = 1;
		  signed_flag_= false;
		  return expr_width_;
	    }
	    return 0;
      }

      // Class variables. In this case, the search found the class instance,
      // and the scope is the scope where the instance lives. The class method
      // in turn defines it's own scope. Use that to find the return value.
      if (search_results.net && search_results.net->data_type()==IVL_VT_CLASS) {
	    const netclass_t *class_type = dynamic_cast<const netclass_t*>(search_results.type);
	    ivl_assert(*this, class_type);
	    NetScope*method = class_type->method_from_name(method_name);

	    if (method == 0) {
		  return 0;
	    }

	    if (debug_elaborate) {
		  cerr << get_fileline() << ": PECallFunction::test_width_method_: "
		       << "Found method " << scope_path(method) << "(...)" << endl;
	    }

	    // Get the return value of the method function.
	    if (NetNet*res = method->find_signal(method->basename())) {
		  expr_type_   = res->data_type();
		  expr_width_  = res->vector_width();
		  min_width_   = expr_width_;
		  signed_flag_ = res->get_signed();

		  if (debug_elaborate) {
			cerr << get_fileline() << ": PECallFunction::test_width_method_: "
			     << "test_width of class method returns width " << expr_width_
			     << ", type=" << expr_type_
			     << "." << endl;
		  }
		  return expr_width_;
	    }
	    return 0;
      }

      if (debug_elaborate) {
	    cerr << get_fileline() << ": PECallFunction::test_width_method_: "
		 << "I give up." << endl;
      }
      return 0;
}

unsigned PECallFunction::test_width(Design*des, NetScope*scope,
                                    width_mode_t&mode)
{
      if (debug_elaborate) {
	    cerr << get_fileline() << ": PECallFunction::test_width: "
		 << "path_: " << path_ << endl;
	    cerr << get_fileline() << ": PECallFunction::test_width: "
		 << "mode: " << width_mode_name(mode) << endl;
      }

      if (peek_tail_name(path_)[0] == '$')
	    return test_width_sfunc_(des, scope, mode);

      // Search for the symbol. This should turn up a scope.
      symbol_search_results search_results;
      bool search_flag = symbol_search(this, des, scope, path_, UINT_MAX, &search_results);

      if (debug_elaborate) {
	    cerr << get_fileline() << ": PECallFunction::test_width: "
		 << "search_flag: " << (search_flag? "true" : "false") << endl;
	    if (search_results.scope)
		  cerr << get_fileline() << ": PECallFunction::test_width: "
		       << "search_results.scope: " << scope_path(search_results.scope) << endl;
	    if (search_results.net)
		  cerr << get_fileline() << ": PECallFunction::test_width: "
		       << "search_results.net: " << search_results.net->name() << endl;
	    cerr << get_fileline() << ": PECallFunction::test_width: "
		 << "search_results.path_head: " << search_results.path_head << endl;
	    cerr << get_fileline() << ": PECallFunction::test_width: "
		 << "search_results.path_tail: " << search_results.path_tail << endl;
      }

      // Nothing found? Return nothing.
      if (!search_flag) {
	    expr_width_ = 0;
	    min_width_ = 0;
	    signed_flag_ = false;
	    if (debug_elaborate) {
		  cerr << get_fileline() << ": PECallFunction::test_width: "
		       << "Not found, returning nil width results." << endl;
	    }
	    return expr_width_;
      }

      // Catch the special case that this is not a scope, but that we
      // are in fact in a function calling ourself recursively. For
      // example:
      //
      //   function integer factoral;
      //      input integer n;
      //      begin
      //        if (n > 1)
      //          factorial = n * factorial(n-1); <== HERE
      //        else
      //          factorial = n;
      //      end
      //    endfunction
      //
      // In this case, the call to factorial within itself will find the
      // net "factorial", but we can notice that the scope is a function
      // with the same name as the function.
      if (test_function_return_value(search_results)) {

	    if (debug_elaborate) {
		  cerr << get_fileline() << ": PECallFunction::test_width: "
		       << "Net " << search_results.net->name()
		       << " is actually a function call to " << scope_path(search_results.scope)
		       << "." << endl;
	    }

	    NetNet*res = search_results.net;
	    expr_type_   = res->data_type();
	    expr_width_  = res->vector_width();
            min_width_   = expr_width_;
            signed_flag_ = res->get_signed();

	    if (debug_elaborate)
		  cerr << get_fileline() << ": PECallFunction::test_width: "
		       << "test_width of function returns width " << dec << expr_width_
		       << ", type=" << expr_type_
		       << "." << endl;

	    return expr_width_;

      }

      // If the symbol is found, but is not a scope...
      if (!search_results.is_scope()) {

	    if (!search_results.path_tail.empty()) {
		  return test_width_method_(des, scope, search_results, mode);
	    }

	    // I don't know what to do about this.
	    if (debug_elaborate) {
		  cerr << get_fileline() << ": PECallFunction::test_width: "
		       << "I don't know how to handle non-scopes here." << endl;
	    }
	    return 0;
      }


      NetFuncDef*def = find_function_definition(des, scope, search_results.scope);
      if (def == 0) {
	    // If this is an access function, then the width and
	    // type are known by definition.
	    if (find_access_function(path_)) {
		  expr_type_   = IVL_VT_REAL;
		  expr_width_  = 1;
		  min_width_   = 1;
                  signed_flag_ = true;

		  return expr_width_;
	    }

	    // I don't know what to do about this.
	    if (debug_elaborate) {
		  cerr << get_fileline() << ": PECallFunction::test_width: "
		       << "Scope is not a function." << endl;
	    }
	    return 0;
      }

      if (def->is_void())
	    return 0;

      NetScope*dscope = def->scope();
      ivl_assert(*this, dscope);

      if (NetNet*res = dscope->find_signal(dscope->basename())) {
	    expr_type_   = res->data_type();
	    expr_width_  = res->vector_width();
            min_width_   = expr_width_;
            signed_flag_ = res->get_signed();

	    if (debug_elaborate)
		  cerr << get_fileline() << ": PECallFunction::test_width: "
		       << "test_width of function returns width " << expr_width_
		       << ", type=" << expr_type_
		       << "." << endl;

	    return expr_width_;
      }

      ivl_assert(*this, 0);
      return 0;
}

NetExpr*PECallFunction::cast_to_width_(NetExpr*expr, unsigned wid) const
{
      if (debug_elaborate) {
            cerr << get_fileline() << ": PECallFunction::cast_to_width_: "
		 << "cast to " << wid
                 << " bits " << (signed_flag_ ? "signed" : "unsigned")
		 << " from expr_width()=" << expr->expr_width() << endl;
      }

      return cast_to_width(expr, wid, signed_flag_, *this);
}

/*
 * Given a call to a system function, generate the proper expression
 * nodes to represent the call in the netlist. Since we don't support
 * size_tf functions, make assumptions about widths based on some
 * known function names.
 */
NetExpr* PECallFunction::elaborate_sfunc_(Design*des, NetScope*scope,
                                          unsigned expr_wid,
                                          unsigned flags) const
{
      perm_string name = peek_tail_name(path_);

      // System functions don't have named parameters
      for (const auto &parm : parms_) {
	    if (!parm.name.nil()) {
		  des->errors++;
		  cerr << parm.get_fileline() << ": error: "
		       << "The system function `" << name
		       << "` has no argument called `" << parm.name << "`."
		       << endl;
	    }
      }

	/* Catch the special case that the system function is the
	   $ivl_unsigned function. In this case the second argument is
	   the size of the expression, but should already be accounted
	   for so treat this very much like the $unsigned() function. */
      if (name=="$ivlh_to_unsigned") {
	    ivl_assert(*this, parms_.size()==2);

	    PExpr *expr = parms_[0].parm;
	    ivl_assert(*this, expr);
	    NetExpr*sub = expr->elaborate_expr(des, scope, expr->expr_width(), flags);
	    return cast_to_width_(sub, expr_wid);
      }

	/* Catch the special case that the system function is the $signed
	   function. Its argument will be evaluated as a self-determined
           expression. */
      if (name=="$signed" || name=="$unsigned") {
	    if ((parms_.size() != 1) || !parms_[0].parm) {
		  cerr << get_fileline() << ": error: The " << name
		       << " function takes exactly one(1) argument." << endl;
		  des->errors += 1;
		  return 0;
	    }

            if (!type_is_vectorable(expr_type_)) {
	          cerr << get_fileline() << ": error: The argument to "
		       << name << " must be a vector type." << endl;
	          des->errors += 1;
	          return 0;
            }

	    if (debug_elaborate) {
		  cerr << get_fileline() << ": PECallFunction::elaborate_sfunc_: "
		       << name << " expression is the argument cast to expr_wid=" << expr_wid << endl;
	    }
	    PExpr *expr = parms_[0].parm;
	    NetExpr*sub = expr->elaborate_expr(des, scope, expr_width_, flags);

	    return cast_to_width_(sub, expr_wid);
      }

	/* Interpret the internal $sizeof system function to return
	   the bit width of the sub-expression. The value of the
	   sub-expression is not used, so the expression itself can be
	   deleted. */
      if (name=="$sizeof" || name=="$bits") {
	    if ((parms_.size() != 1) || !parms_[0].parm) {
		  cerr << get_fileline() << ": error: The " << name
		       << " function takes exactly one(1) argument." << endl;
		  des->errors += 1;
		  return 0;
	    }

	    if (name=="$sizeof")
		  cerr << get_fileline() << ": warning: $sizeof is deprecated."
		       << " Use $bits() instead." << endl;

	    PExpr *expr = parms_[0].parm;

	    uint64_t use_width = 0;
	    if (PETypename*type_expr = dynamic_cast<PETypename*>(expr)) {
		  ivl_type_t data_type = type_expr->get_type()->elaborate_type(des, scope);
		  ivl_assert(*this, data_type);
		  use_width = 1;
		  while (const netuarray_t *utype =
			 dynamic_cast<const netuarray_t*>(data_type)) {
			use_width = netrange_width(utype->static_dimensions(),
			                           use_width);
			data_type = utype->element_type();
		  }
		  if (!data_type->packed()) {
			use_width = 0;
			cerr << get_fileline() << ": error: "
			     << "Invalid data type for $bits()."
			     << endl;
			des->errors++;
		  } else {
			use_width *= data_type->packed_width();
		  }
		  if (debug_elaborate) {
			cerr << get_fileline() << ": PECallFunction::elaborate_sfunc_: "
			     << " Packed width of type argument is " << use_width << endl;
		  }

	    } else {
		  use_width = expr->expr_width();
		  if (debug_elaborate) {
			cerr << get_fileline() << ": PECallFunction::elaborate_sfunc_: "
			     << " Width of expression argument is " << use_width << endl;
		  }
	    }

	    verinum val (use_width, integer_width);
	    NetEConst*sub = new NetEConst(val);
	    sub->set_line(*this);

	    return cast_to_width_(sub, expr_wid);
      }

	/* Interpret the internal $is_signed system function to return
	   a single bit flag -- 1 if the expression is signed, 0
	   otherwise. */
      if (name=="$is_signed") {
	    if ((parms_.size() != 1) || !parms_[0].parm) {
		  cerr << get_fileline() << ": error: The " << name
		       << " function takes exactly one(1) argument." << endl;
		  des->errors += 1;
		  return 0;
	    }

	    PExpr *expr = parms_[0].parm;

	    verinum val (expr->has_sign() ? verinum::V1 : verinum::V0, 1);
	    NetEConst*sub = new NetEConst(val);
	    sub->set_line(*this);

	    return cast_to_width_(sub, expr_wid);
      }

      unsigned nparms = parms_.size();

      NetESFunc*fun = new NetESFunc(name, expr_type_, expr_width_, nparms, is_overridden_);
      fun->set_line(*this);

      bool need_const = NEED_CONST & flags;

	/* We don't support evaluating overridden functions. */
      if (is_overridden_ && (need_const || scope->need_const_func())) {
	    cerr << get_fileline() << ": sorry: Cannot evaluate "
		    "overridden system function." << endl;
	    des->errors += 1;
      }

      if (is_overridden_ || !fun->is_built_in()) {
	    if (scope->need_const_func()) {
		  cerr << get_fileline() << ": error: " << name
		       << " is not a built-in function, so cannot"
		       << " be used in a constant function." << endl;
		  des->errors += 1;
	    }
	    scope->is_const_func(false);
      }

	/* Now run through the expected parameters. If we find that
	   there are missing parameters, print an error message.

	   While we're at it, try to evaluate the function parameter
	   expression as much as possible, and use the reduced
	   expression if one is created. */

	/* These functions can work in a constant context with a signal expression. */
      if ((nparms == 1) && (dynamic_cast<PEIdent*>(parms_[0].parm))) {
	    if (strcmp(name, "$dimensions") == 0) need_const = false;
	    else if (strcmp(name, "$high") == 0) need_const = false;
	    else if (strcmp(name, "$increment") == 0) need_const = false;
	    else if (strcmp(name, "$left") == 0) need_const = false;
	    else if (strcmp(name, "$low") == 0) need_const = false;
	    else if (strcmp(name, "$right") == 0) need_const = false;
	    else if (strcmp(name, "$size") == 0) need_const = false;
	    else if (strcmp(name, "$unpacked_dimensions") == 0) need_const = false;
      }

      unsigned parm_errors = 0;
      unsigned missing_parms = 0;
      for (unsigned idx = 0 ;  idx < nparms ;  idx += 1) {
	    PExpr *expr = parms_[idx].parm;
	    if (expr) {
		  NetExpr*tmp = elab_sys_task_arg(des, scope, name, idx,
                                                  expr, need_const);
                  if (tmp) {
                        fun->parm(idx, tmp);
                  } else {
                        parm_errors += 1;
                        fun->parm(idx, 0);
                  }
	    } else {
		  missing_parms += 1;
		  fun->parm(idx, 0);
	    }
      }

      if (missing_parms > 0) {
	    cerr << get_fileline() << ": error: The function " << name
		 << " has been called with missing/empty parameters." << endl;
	    cerr << get_fileline() << ":      : Verilog doesn't allow "
		 << "passing empty parameters to functions." << endl;
	    des->errors += 1;
      }

      if (missing_parms || parm_errors)
            return 0;

      return pad_to_width(fun, expr_wid, signed_flag_, *this);
}

NetExpr* PECallFunction::elaborate_access_func_(Design*des, NetScope*scope,
						ivl_nature_t nature) const
{
	// An access function must have 1 or 2 arguments.
      ivl_assert(*this, parms_.size()==2 || parms_.size()==1);

      NetBranch*branch = 0;

      if (parms_.size() == 1) {
	    PExpr *arg1 = parms_[0].parm;
	    PEIdent*arg_ident = dynamic_cast<PEIdent*> (arg1);
	    ivl_assert(*this, arg_ident);

	    const pform_name_t&path = arg_ident->path().name;
	    ivl_assert(*this, path.size()==1);
	    perm_string name = peek_tail_name(path);

	    NetNet*sig = scope->find_signal(name);
	    ivl_assert(*this, sig);

	    ivl_discipline_t dis = sig->get_discipline();
	    ivl_assert(*this, dis);
	    ivl_assert(*this, nature == dis->potential() || nature == dis->flow());

	    NetNet*gnd = des->find_discipline_reference(dis, scope);

	    if ( (branch = find_existing_implicit_branch(sig, gnd)) ) {
		  if (debug_elaborate)
			cerr << get_fileline() << ": debug: "
			     << "Re-use implicit branch from "
			     << branch->get_fileline() << endl;
	    } else {
		  branch = new NetBranch(dis);
		  branch->set_line(*this);
		  connect(branch->pin(0), sig->pin(0));
		  connect(branch->pin(1), gnd->pin(0));

		  des->add_branch(branch);
		  join_island(branch);

		  if (debug_elaborate)
			cerr << get_fileline() << ": debug: "
			     << "Create implicit branch." << endl;

	    }

      } else {
	    ivl_assert(*this, 0);
      }

      NetExpr*tmp = new NetEAccess(branch, nature);
      tmp->set_line(*this);
      return tmp;
}

/*
 * Routine to look for and build enumeration method calls.
 */
static NetExpr* check_for_enum_methods(const LineInfo*li,
                                       Design*des, NetScope*scope,
                                       const netenum_t*netenum,
                                       const pform_scoped_name_t&use_path,
                                       perm_string method_name,
                                       NetExpr*expr,
                                       const std::vector<named_pexpr_t> &parms)
{
      if (debug_elaborate) {
	    cerr << li->get_fileline() << ": " << __func__ << ": "
		 << "Check for method " << method_name
		 << " of enumeration at " << netenum->get_fileline()
		 << endl;
	    cerr << li->get_fileline() << ": " << __func__ << ": "
		 << "use_path=" << use_path << endl;
	    cerr << li->get_fileline() << ": " << __func__ << ": "
		 << "expr=" << *expr << endl;
      }

      // First, look for some special methods that can be replace with
      // constant literals. These get properties of the enumeration type, and
      // so can be fully evaluated at compile time.

      if (method_name == "num") {
	    // The "num()" method returns the number of elements. This is
	    // actually a static constant, and can be replaced at compile time
	    // with a constant value.
	    if (parms.size() != 0) {
		  cerr << li->get_fileline() << ": error: enumeration "
		          "method " << use_path << " does not "
		          "take an argument." << endl;
		  des->errors += 1;
	    }
	    NetEConst*tmp = make_const_val(netenum->size());
	    tmp->set_line(*li);
	    delete expr; // The elaborated enum variable is not needed.
	    return tmp;
      }

      if (method_name == "first") {
	    // The "first()" method returns the first enumeration value. This
	    // doesn't actually care about the constant value, and instead
	    // returns as a constant literal the first value of the enumeration.
	    if (parms.size() != 0) {
		  cerr << li->get_fileline() << ": error: enumeration "
		          "method " << use_path << " does not "
		          "take an argument." << endl;
		  des->errors += 1;
	    }
	    netenum_t::iterator item = netenum->first_name();
	    NetEConstEnum*tmp = new NetEConstEnum(item->first, netenum, item->second);
	    tmp->set_line(*li);
	    delete expr; // The elaborated enum variable is not needed.
	    return tmp;
      }

      if (method_name == "last") {
	    // The "last()" method returns the first enumeration value. This
	    // doesn't actually care about the constant value, and instead
	    // returns as a constant literal the last value of the enumeration.
	    if (parms.size() != 0) {
		  cerr << li->get_fileline() << ": error: enumeration "
		          "method " << use_path << " does not "
		          "take an argument." << endl;
		  des->errors += 1;
	    }
	    netenum_t::iterator item = netenum->last_name();
	    NetEConstEnum*tmp = new NetEConstEnum(item->first, netenum, item->second);
	    tmp->set_line(*li);
	    delete expr; // The elaborated enum variable is not needed.
	    return tmp;
      }

      NetESFunc*sys_expr;

      if (method_name == "name") {
	    // The "name()" method returns the name of the current enumeration
	    // value. The generated system task takes the enumeration
	    // definition and the enumeration value. The return value is the
	    // string name of the enumeration.
	    if (parms.size() != 0) {
		  cerr << li->get_fileline() << ": error: enumeration "
		          "method " << use_path << " does not "
		          "take an argument." << endl;
		  des->errors += 1;
	    }

	    // Generate the internal system function. Make sure the return
	    // value is "string" type.
	    sys_expr = new NetESFunc("$ivl_enum_method$name",
				     &netstring_t::type_string, 2);
	    NetENetenum* def = new NetENetenum(netenum);
	    def->set_line(*li);
	    sys_expr->parm(0, def);
	    sys_expr->parm(1, expr);

      } else if (method_name == "next" || method_name == "prev") {
	    static const std::vector<perm_string> parm_names = {
		  perm_string::literal("N"),
	    };
	    auto args = map_named_args(des, parm_names, parms);

	      // Process the method argument if it is available.
	    NetExpr *count = nullptr;
	    if (args.size() != 0 && args[0]) {
		  count = elaborate_rval_expr(des, scope, &netvector_t::atom2u32,
					      args[0]);
		  if (!count) {
			cerr << li->get_fileline() << ": error: unable to elaborate "
				"enumeration method argument " << use_path << "."
			     << method_name << "(" << args[0] << ")." << endl;
			des->errors++;
		  } else if (NetEEvent *evt = dynamic_cast<NetEEvent*> (count)) {
			cerr << evt->get_fileline() << ": error: An event '"
			     << evt->event()->name() << "' cannot be an enumeration "
				"method argument." << endl;
			des->errors++;
		  }
	    }

	    // The "next()" and "prev()" methods returns the next or previous enumeration value.
	    if (args.size() > 1) {
		  cerr << li->get_fileline() << ": error: enumeration "
		          "method " << use_path << " takes at "
		          "most one argument." << endl;
		  des->errors += 1;
	    }

	    const char *func_name;
	    if (method_name == "next")
		  func_name = "$ivl_enum_method$next";
	    else
		  func_name = "$ivl_enum_method$prev";

	    sys_expr = new NetESFunc(func_name, netenum,
	                             2 + (count != nullptr));
	    NetENetenum* def = new NetENetenum(netenum);
	    def->set_line(*li);
	    sys_expr->parm(0, def);
	    sys_expr->parm(1, expr);
	    if (count) sys_expr->parm(2, count);

      } else {
	    // This is an unknown enumeration method.
	    cerr << li->get_fileline() << ": error: Unknown enumeration "
	            "method " << use_path << "." << method_name << "()."
	         << endl;
	    des->errors += 1;
	    return expr;
      }

      sys_expr->set_line(*li);

      if (debug_elaborate) {
	    cerr << li->get_fileline() << ": " << __func__ << ": Generate "
	         << sys_expr->name() << "(" << use_path << ")" << endl;
      }

      return sys_expr;
}

bool calculate_part(const LineInfo*li, Design*des, NetScope*scope,
		    const index_component_t&index, long&off, unsigned long&wid)
{
      if (index.sel == index_component_t::SEL_BIT_LAST) {
	    cerr << li->get_fileline() << ": sorry: "
		 << "Last element select expression "
		 << "not supported." << endl;
	    des->errors += 1;
	    return false;
      }

	// Evaluate the last index expression into a constant long.
      NetExpr*texpr = elab_and_eval(des, scope, index.msb, -1, true);
      long msb;
      if (texpr == 0 || !eval_as_long(msb, texpr)) {
	    cerr << li->get_fileline() << ": error: "
		  "Array/part index expressions must be constant here." << endl;
	    des->errors += 1;
	    return false;
      }

      delete texpr;

      long lsb = msb;
      if (index.lsb) {
	    texpr = elab_and_eval(des, scope, index.lsb, -1, true);
	    if (texpr==0 || !eval_as_long(lsb, texpr)) {
		  cerr << li->get_fileline() << ": error: "
			"Array/part index expressions must be constant here." << endl;
		  des->errors += 1;
		  return false;
	    }

	    delete texpr;
      }

      switch (index.sel) {
	  case index_component_t::SEL_BIT:
	    off = msb;
	    wid = 1;
	    return true;

	  case index_component_t::SEL_PART:
	    off = lsb;
	    if (msb >= lsb) {
		  wid = msb - lsb + 1;
	    } else {
		  wid = lsb - msb + 1;
	    }
	    return true;

	  case index_component_t::SEL_IDX_UP:
	    wid = lsb;
	    off = msb;
	    break;

	  default:
	    ivl_assert(*li, 0);
	    break;
      }
      return true;
}

/*
 * Test if the tail name (method_name argument) is a member name and
 * the net is a struct. If that turns out to be the case, and the
 * struct is packed, then return a NetExpr that selects the member out
 * of the variable.
 */
static NetExpr* check_for_struct_members(const LineInfo*li,
					 Design*des, NetScope*scope,
					 NetNet*net,
					 const list<index_component_t>&base_index,
					 pform_name_t member_path)
{
      const netstruct_t*struct_type = net->struct_type();
      ivl_assert(*li, struct_type);

      if (! struct_type->packed()) {
	    cerr << li->get_fileline() << ": sorry: "
		 << "Unpacked structures not supported here."
		 << endl;
	    des->errors += 1;
	    return 0;
      }

	// These make up the "part" select that is the equivilent of
	// following the member path through the nested structs. To
	// start with, the off[set] is zero, and use_width is the
	// width of the entire variable. The first member_comp is at
	// some offset within the variable, and will have a reduced
	// width. As we step through the member_path the off
	// increases, and use_width shrinks.
      unsigned long off = 0;
      unsigned long use_width = struct_type->packed_width();

      pform_name_t completed_path;
      ivl_type_t member_type = 0;
      do {
	    const name_component_t member_comp = member_path.front();
	    const perm_string&member_name = member_comp.name;

	    if (debug_elaborate) {
		  cerr << li->get_fileline() << ": check_for_struct_members: "
		       << "Processing member_comp=" << member_comp
		       << " (completed_path=" << completed_path << ")"
		       << endl;
	    }

	      // Calculate the offset within the packed structure of the
	      // member, and any indices. We will add in the offset of the
	      // struct into the packed array later. Note that this works
	      // for packed unions as well (although the offset will be 0
	      // for union members).
	    unsigned long tmp_off;
	    const netstruct_t::member_t* member = struct_type->packed_member(member_name, tmp_off);

	    if (member == 0) {
		  cerr << li->get_fileline() << ": error: Member " << member_name
		       << " is not a member of struct type of "
		       << net->name()
		       << "." << completed_path << endl;
		  des->errors += 1;
		  return 0;
	    }
	    member_type = member->net_type;
	    if (debug_elaborate) {
		  cerr << li->get_fileline() << ": check_for_struct_members: "
		       << "Member type: " << *member_type
		       << " (" << typeid(*member_type).name() << ")"
		       << endl;
	    }

	    off += tmp_off;
	    ivl_assert(*li, use_width >= (unsigned long)member_type->packed_width());
	    use_width = member_type->packed_width();

	      // At this point, off and use_width are the part select
	      // expressed by the member_comp, which is a member of the
	      // struct. We can further refine the part select with any
	      // indices that might be present.

	    if (const netstruct_t*tmp_struct = dynamic_cast<const netstruct_t*>(member_type)) {
		    // If the member is itself a struct, then get
		    // ready to go on to the next iteration.
		  struct_type = tmp_struct;

	    } else if (const netenum_t*tmp_enum = dynamic_cast<const netenum_t*> (member_type)) {

		    // If the element is an enum, then we only need to check if
		    // there is a part select for it
		  if (debug_elaborate) {
			cerr << li->get_fileline() << ": check_for_struct_members: "
			     << "Tail element is an enum" << *tmp_enum
			     << endl;
		  }
		  struct_type = 0;

		  if (!member_comp.index.empty()) {

			if (member_comp.index.size() > 1) {
			      cerr << li->get_fileline() << ": error: "
				   << "Too many index expressions for enum member." << endl;
			      des->errors += 1;
			      return 0;
			}

			long tail_off = 0;
			unsigned long tail_wid = 0;
			bool rc = calculate_part(li, des, scope, member_comp.index.back(), tail_off, tail_wid);
			if (! rc) return 0;

			off += tail_off;
			use_width = tail_wid;
		  }

	    } else if (const netvector_t*mem_vec = dynamic_cast<const netvector_t*>(member_type)) {

		  if (debug_elaborate) {
			cerr << li->get_fileline() << ": check_for_struct_members: "
			     << "member_comp=" << member_comp
			     << " has " << member_comp.index.size() << " indices."
			     << endl;
		  }

		    // If the member type is a netvector_t, then it is a
		    // vector of atom or scaler objects. For example, if the
		    // l-value expression is "foo.member[1][2]",
		    // then the member should be something like:
		    //    ... logic [h:l][m:n] member;
		    // There should be index expressions index the vector
		    // down, but there doesn't need to be all of them. We
		    // can, for example, be selecting a part of the vector.

		    // We only need to process this if there are any
		    // index expressions. If not, then the packed
		    // vector can be handled atomically.

		    // In any case, this should be the tail of the
		    // member_path, because the array element of this
		    // kind of array cannot be a struct.
		  if (!member_comp.index.empty()) {
			  // These are the dimensions defined by the type
			const netranges_t&mem_packed_dims = mem_vec->packed_dims();

			if (member_comp.index.size() > mem_packed_dims.size()) {
			      cerr << li->get_fileline() << ": error: "
				   << "Too many index expressions for member." << endl;
			      des->errors += 1;
			      return 0;
			}

			  // Evaluate all but the last index expression, into prefix_indices.
			list<long>prefix_indices;
			bool rc = evaluate_index_prefix(des, scope, prefix_indices, member_comp.index);
			ivl_assert(*li, rc);

			if (debug_elaborate) {
			      cerr << li->get_fileline() << ": check_for_struct_members: "
				   << "prefix_indices.size()==" << prefix_indices.size()
				   << ", mem_packed_dims.size()==" << mem_packed_dims.size()
				   << endl;
			}

			long tail_off = 0;
			unsigned long tail_wid = 0;
			rc = calculate_part(li, des, scope, member_comp.index.back(), tail_off, tail_wid);
			if (! rc) return 0;

			if (debug_elaborate) {
			      cerr << li->get_fileline() << ": check_for_struct_member: "
				   << "calculate_part for tail returns tail_off=" << tail_off
				   << ", tail_wid=" << tail_wid
				   << endl;
			}


			  // Now use the prefix_to_slice function to calculate the
			  // offset and width of the addressed slice
			  // of the member. The lwid comming out of
			  // the prefix_to_slice is the number of
			  // elements, and should be 1. The tmp_wid it
			  // the bit with of the result.
			long loff;
			unsigned long lwid;
			prefix_to_slice(mem_packed_dims, prefix_indices, tail_off, loff, lwid);

			if (debug_elaborate) {
			      cerr << li->get_fileline() << ": check_for_struct_members: "
				   << "Calculate loff=" << loff << " lwid=" << lwid
				   << " tail_off=" << tail_off << " tail_wid=" << tail_wid
				   << " off=" << off << " use_width=" << use_width
				   << endl;
			}

			off += loff;
			use_width = lwid * tail_wid;
		  }

		    // The netvector_t only has atom elements, so
		    // there is no next struct type.
		  struct_type = 0;

	    } else if (const netparray_t*array = dynamic_cast<const netparray_t*>(member_type)) {

		    // If the member is a parray, then the elements
		    // are themselves packed object, including
		    // possibly a struct. Handle this by taking the
		    // part select of the current part of the
		    // variable, then stepping to the element type to
		    // possibly iterate through more of the member_path.
		  ivl_assert(*li, array->packed());
		  ivl_assert(*li, !member_comp.index.empty());

		    // These are the dimensions defined by the type
		  const netranges_t&mem_packed_dims = array->static_dimensions();

		  if (member_comp.index.size() != mem_packed_dims.size()) {
			cerr << li->get_fileline() << ": error: "
			     << "Incorrect number of index expressions for member "
			     << member_name << "." << endl;
			des->errors += 1;
			return 0;
		  }

		    // Evaluate all but the last index expression, into prefix_indices.
		  list<long>prefix_indices;
		  bool rc = evaluate_index_prefix(des, scope, prefix_indices, member_comp.index);
		  ivl_assert(*li, rc);

		    // Evaluate the last index expression into a constant long.
		  NetExpr*texpr = elab_and_eval(des, scope, member_comp.index.back().msb, -1, true);
		  long tmp;
		  if (texpr == 0 || !eval_as_long(tmp, texpr)) {
			cerr << li->get_fileline() << ": error: "
			     << "Array index expressions for member " << member_name
			     << " must be constant here." << endl;
			des->errors += 1;
			return 0;
		  }

		  delete texpr;

		    // Now use the prefix_to_slice function to calculate the
		    // offset and width of the addressed slice of the member.
		  long loff;
		  unsigned long lwid;
		  prefix_to_slice(mem_packed_dims, prefix_indices, tmp, loff, lwid);

		  ivl_type_t element_type = array->element_type();
		  long element_width = element_type->packed_width();
		  if (debug_elaborate) {
			cerr << li->get_fileline() << ": PEIdent::elaborate_lval_net_packed_member_: "
			     << "parray subselection loff=" << loff
			     << ", lwid=" << lwid
			     << ", element_width=" << element_width
			     << endl;
		  }

		    // The width and offset calculated from the
		    // indices is actually in elements, and not
		    // bits. In fact, in this context, the lwid should
		    // come down to 1 (one element).
		  off += loff * element_width;
		  ivl_assert(*li, lwid==1);
		  use_width = element_width;

		    // To move on to the next component in the member
		    // path, get the element type. For example, for
		    // the path a.b[1].c, we are processing b[1] here,
		    // and the element type should be a netstruct_t
		    // that will wind up containing the member c.
		  struct_type = dynamic_cast<const netstruct_t*> (element_type);

	    } else {
		    // Unknown type?
		  cerr << li->get_fileline() << ": internal error: "
		       << "Unexpected member type? " << *member_type
		       << endl;
		  des->errors += 1;
		  struct_type = 0;
	    }

	      // Complete this component of the path, mark it
	      // completed, and set up for the next component.
	    completed_path .push_back(member_comp);
	    member_path.pop_front();

      } while (!member_path.empty() && struct_type != 0);

	// The dimensions in the expression must match the packed
	// dimensions that are declared for the variable. For example,
	// if foo is a packed array of struct, then this expression
	// must be "b[n][m]" with the right number of dimensions to
	// match the declaration of "b".
	// Note that one of the packed dimensions is the packed struct
	// itself.
      ivl_assert(*li, base_index.size()+1 == net->packed_dimensions());

      NetExpr*packed_base = 0;
      if (net->packed_dimensions() > 1) {
	    list<index_component_t>tmp_index = base_index;
	    index_component_t member_select;
	    member_select.sel = index_component_t::SEL_BIT;
	    member_select.msb = new PENumber(new verinum(off));
	    tmp_index.push_back(member_select);
	    packed_base = collapse_array_exprs(des, scope, li, net, tmp_index);
	    ivl_assert(*li, packed_base);
	    if (debug_elaborate) {
		  cerr << li->get_fileline() << ": debug: check_for_struct_members: "
		       << "Got collapsed array expr: " << *packed_base << endl;
	    }
      }

      long tmp;
      if (packed_base && eval_as_long(tmp, packed_base)) {
	    off += tmp;
	    delete packed_base;
	    packed_base = 0;
      }

      NetESignal*sig = new NetESignal(net);
      NetExpr   *base = packed_base? packed_base : make_const_val(off);
      NetESelect*sel = new NetESelect(sig, base, use_width, member_type);

      if (debug_elaborate) {
	    cerr << li->get_fileline() << ": check_for_struct_member: "
		 << "Finally, completed_path=" << completed_path
		 << ", off=" << off << ", use_width=" << use_width
		 << ", base=" << *base
		 << endl;
      }

      return sel;
}

static NetExpr* class_static_property_expression(const LineInfo*li,
						 const netclass_t*class_type,
						 perm_string name)
{
      NetNet*sig = class_type->find_static_property(name);
      ivl_assert(*li, sig);
      NetESignal*expr = new NetESignal(sig);
      expr->set_line(*li);
      return expr;
}

NetExpr* PEIdent::elaborate_expr_class_field_(Design*des, NetScope*scope,
					      const symbol_search_results &sr,
					      unsigned expr_wid,
					      unsigned flags) const
{

      const netclass_t *class_type = dynamic_cast<const netclass_t*>(sr.type);
      const name_component_t comp = sr.path_tail.front();

      if (debug_elaborate) {
	    cerr << get_fileline() << ": PEIdent::elaborate_expr: "
		 << "Ident " << sr.path_head
		 << " look for property " << comp << endl;
      }

      if (sr.path_tail.size() > 1) {
	    cerr << get_fileline() << ": sorry: "
		 << "Nested member path not yet supported for class properties."
		 << endl;
	    return nullptr;
      }

      ivl_type_t par_type;
      const NetExpr *par_val = class_type->get_parameter(des, comp.name, par_type);
      if (par_val)
	    return elaborate_expr_param_(des, scope, par_val,
				         class_type->class_scope(), par_type,
				         expr_wid, flags);

      int pidx = class_type->property_idx_from_name(comp.name);
      if (pidx < 0) {
	    cerr << get_fileline() << ": error: "
		 << "Class " << class_type->get_name()
		 << " has no property " << comp.name << "." << endl;
	    des->errors += 1;
	    return 0;
      }

      if (debug_elaborate) {
	    cerr << get_fileline() << ": check_for_class_property: "
		 << "Property " << comp.name
		 << " of net " << sr.net->name()
		 << ", context scope=" << scope_path(scope)
		 << endl;
      }

      property_qualifier_t qual = class_type->get_prop_qual(pidx);
      if (qual.test_local() && ! class_type->test_scope_is_method(scope)) {
	    cerr << get_fileline() << ": error: "
		 << "Local property " << class_type->get_prop_name(pidx)
		 << " is not accessible in this context."
		 << " (scope=" << scope_path(scope) << ")" << endl;
	    des->errors += 1;
      }

      if (qual.test_static()) {
	    perm_string prop_name = lex_strings.make(class_type->get_prop_name(pidx));
	    return class_static_property_expression(this, class_type,
						    prop_name);
      }

      NetExpr *canon_index = nullptr;
      ivl_type_t tmp_type = class_type->get_prop_type(pidx);
      if (const netuarray_t *tmp_ua = dynamic_cast<const netuarray_t*>(tmp_type)) {
	    const auto &dims = tmp_ua->static_dimensions();

	    if (debug_elaborate) {
		  cerr << get_fileline() << ": PEIdent::elaborate_expr_class_member_: "
		       << "Property " << class_type->get_prop_name(pidx)
		       << " has " << dims.size() << " dimensions, "
		       << " got " << comp.index.size() << " indices." << endl;
	    }

	    if (dims.size() != comp.index.size()) {
		  cerr << get_fileline() << ": error: "
		       << "Got " << comp.index.size() << " indices, "
		       << "expecting " << dims.size()
		       << " to index the property " << class_type->get_prop_name(pidx) << "." << endl;
		  des->errors++;
	    } else {
		  canon_index = make_canonical_index(des, scope, this,
						     comp.index, tmp_ua, false);
	    }
      }

      if (debug_elaborate && canon_index) {
	    cerr << get_fileline() << ": PEIdent::elaborate_expr_class_member_: "
		 << "Property " << class_type->get_prop_name(pidx)
		 << " canonical index: " << *canon_index << endl;
      }

      NetEProperty *tmp = new NetEProperty(sr.net, pidx, canon_index);
      tmp->set_line(*this);
      return tmp;
}

NetExpr* PECallFunction::elaborate_expr(Design*des, NetScope*scope,
					unsigned expr_wid, unsigned flags) const
{
      if (debug_elaborate) {
	    cerr << get_fileline() << ": PECallFunction::elaborate_expr: "
		 << "path_: " << path_ << endl;
	    cerr << get_fileline() << ": PECallFunction::elaborate_expr: "
		 << "expr_wid: " << expr_wid << endl;
      }

      if (peek_tail_name(path_)[0] == '$')
	    return elaborate_sfunc_(des, scope, expr_wid, flags);

      NetExpr *result = elaborate_expr_(des, scope, flags);
      if (!result || !type_is_vectorable(expr_type_))
	    return result;

      return pad_to_width(result, expr_wid, signed_flag_, *this);
}

NetExpr* PECallFunction::elaborate_expr_(Design*des, NetScope*scope,
					 unsigned flags) const
{
      flags &= ~SYS_TASK_ARG; // don't propagate the SYS_TASK_ARG flag

      // Search for the symbol. This should turn up a scope.
      symbol_search_results search_results;
      bool search_flag = symbol_search(this, des, scope, path_, UINT_MAX, &search_results);

      if (debug_elaborate) {
	    cerr << get_fileline() << ": PECallFunction::elaborate_expr: "
		 << "search_flag: " << (search_flag? "true" : "false") << endl;
	    if (search_results.scope)
		  cerr << get_fileline() << ": PECallFunction::elaborate_expr: "
		       << "search_results.scope: " << scope_path(search_results.scope) << endl;
	    if (search_results.net)
		  cerr << get_fileline() << ": PECallFunction::elaborate_expr: "
		       << "search_results.net: " << search_results.net->name() << endl;
	    if (search_results.par_val)
		  cerr << get_fileline() << ": PECallFunction::elaborate_expr: "
		       << "search_results.par_val: " << *search_results.par_val << endl;
	    cerr << get_fileline() << ": PECallFunction::elaborate_expr: "
		 << "search_results.path_head: " << search_results.path_head << endl;
	    cerr << get_fileline() << ": PECallFunction::elaborate_expr: "
		 << "search_results.path_tail: " << search_results.path_tail << endl;
      }

      // If the symbol is not found at all...
      if (!search_flag) {
	    cerr << get_fileline() << ": error: No function named `" << path_
		 << "' found in this context (" << scope_path(scope) << ")."
		 << endl;
	    des->errors += 1;
	    return 0;
      }

      // If the symbol is found, but is not a scope...
      if (! search_results.is_scope() && !test_function_return_value(search_results)) {

	    // Maybe this is a method of an object? Give it a try.
	    if (!search_results.path_tail.empty()) {
		  NetExpr*tmp = elaborate_expr_method_(des, scope, search_results);
		  if (tmp) {
			if (debug_elaborate) {
			      cerr << get_fileline() << ": PECallFunction::elaborate_expr: "
				   << "Elaborated method: " << *tmp << endl;
			}
			return tmp;
		  } else {
			cerr << get_fileline() << ": error: "
			     << "Object " << scope_path(search_results.scope)
			     << "." << search_results.path_head.back()
			     << " has no method \"" << search_results.path_tail
			     << "(...)\"." << endl;
			des->errors += 1;
			return 0;
		  }
	    }

	    cerr << get_fileline() << ": error: Object " << search_results.path_head.back()
		 << " in " << scope_path(search_results.scope)
		 << " is not a function." << endl;
	    des->errors += 1;
	    return 0;
      }

      // If the symbol is found, but is not a _function_ scope...
      if (search_results.scope->type() != NetScope::FUNC) {
	      // Not a user defined function. Maybe it is an access
	      // function for a nature? If so then elaborate it that
	      // way.
	    ivl_nature_t access_nature = find_access_function(path_);
	    if (access_nature)
		  return elaborate_access_func_(des, scope, access_nature);

	      // Nothing was found so report this as an error.
	    cerr << get_fileline() << ": error: No function named `" << path_
	         << "' found in this context (" << scope_path(scope) << ")."
                 << endl;
	    des->errors += 1;
	    return 0;
      }
      NetFuncDef*def = search_results.scope->func_def();

      ivl_assert(*this, def);
      ivl_assert(*this, def->scope() == search_results.scope);
      NetScope*dscope = search_results.scope;

      // In SystemVerilog, a method calling another method in the current
      // class needs to be elaborated as a method with an implicit "this"
      // added. This is a special case. If we detect this case, then
      // synthesize a new symbol_search_results thast properly reflects the
      // implicit "this", and treat this item as a class method.
      if (gn_system_verilog() && (path_.size() == 1)) {
           const NetScope *c_scope = scope->get_class_scope();
           if (c_scope && (c_scope == dscope->get_class_scope())) {
		 if (debug_elaborate) {
		       cerr << get_fileline() << ": PECallFunction::elaborate_expr: "
			    << "Found a class method calling another method." << endl;
		       cerr << get_fileline() << ": PECallFunction::elaborate_expr: "
			    << "scope: " << scope_path(scope) << endl;
		       cerr << get_fileline() << ": PECallFunction::elaborate_expr: "
			    << "c_scope: " << scope_path(c_scope) << endl;
		 }
		 symbol_search_results use_search_results;
		 use_search_results.scope = scope;
		 use_search_results.path_tail.push_back(search_results.path_head.back());
		 use_search_results.path_head.push_back(name_component_t(perm_string::literal(THIS_TOKEN)));
		 use_search_results.net = scope->find_signal(perm_string::literal(THIS_TOKEN));
		 use_search_results.type = use_search_results.net->net_type();
		 ivl_assert(*this, use_search_results.net);

		 return elaborate_expr_method_(des, scope, use_search_results);
           }
      }

      bool need_const = NEED_CONST & flags;

        // It is possible to get here before the called function has been
        // fully elaborated. If this is the case, elaborate it now. This
        // ensures we know whether or not it is a constant function.
      if (dscope->elab_stage() < 3) {
            dscope->need_const_func(need_const || scope->need_const_func());
            const PFunction*pfunc = dscope->func_pform();
            ivl_assert(*this, pfunc);
            pfunc->elaborate(des, dscope);
      }

	// From IEEE 1800-2023 section 13.4.3:
	// A constant function call is a function call of a constant function
	// wherein the constant function's declaration is local to the calling
	// design element or is in a package or $unit.
      bool is_const_func_call = false;
      if (dscope->is_const_func()) {
	    NetScope*caller_scope = scope;
	    while (caller_scope && caller_scope->type() != NetScope::MODULE
				&& caller_scope->type() != NetScope::PACKAGE) {
		  caller_scope = caller_scope->parent();
	    }
	    NetScope*callee_scope = dscope->parent();
	    while (callee_scope && callee_scope->type() != NetScope::MODULE
				&& callee_scope->type() != NetScope::PACKAGE) {
		  callee_scope = callee_scope->parent();
	    }
	    ivl_assert(*this, caller_scope);
	    ivl_assert(*this, callee_scope);
	    is_const_func_call = (callee_scope == caller_scope) ||
				 (callee_scope->type() == NetScope::PACKAGE);
      }
      if (!is_const_func_call) {
            if (scope->need_const_func()) {
	          cerr << get_fileline() << ": error: A function invoked by "
                          "a constant function must be a constant function "
                          "local to the current module or provided by a "
                          "package." << endl;
                  des->errors += 1;
            }
            scope->is_const_func(false);
      }

      return elaborate_base_(des, scope, dscope, flags);
}

NetExpr* PECallFunction::elaborate_expr(Design*des, NetScope*scope,
					ivl_type_t type, unsigned flags) const
{
      const netdarray_t*darray = dynamic_cast<const netdarray_t*>(type);
      unsigned int width = 1;
        // Icarus allows a dynamic array to be initialised with a single
        // elementary value, in that case the expression needs to be evaluated
        // with the rigth width.
      if (darray)
	    width = darray->element_type()->packed_width();
      return elaborate_expr(des, scope, width, flags);
}

NetExpr* PECallFunction::elaborate_base_(Design*des, NetScope*scope, NetScope*dscope,
					 unsigned flags) const
{

      if (! check_call_matches_definition_(des, dscope))
	    return 0;

      NetFuncDef*def = dscope->func_def();

      bool need_const = NEED_CONST & flags;

	// If this is a constant expression, it is possible that we
	// are being elaborated before the function definition. If
	// that's the case, try to elaborate the function as a const
	// function.
      if (need_const && ! def->proc()) {
	    if (debug_elaborate) {
		  cerr << get_fileline() << ": PECallFunction::elaborate_base_: "
		       << "Try to elaborate " << scope_path(dscope)
		       << " as constant function." << endl;
	    }
	    dscope->set_elab_stage(2);
	    dscope->need_const_func(true);
	    const PFunction*pfunc = dscope->func_pform();
	    ivl_assert(*this, pfunc);
	    pfunc->elaborate(des, dscope);
      }

      unsigned parms_count = def->port_count();
      vector<NetExpr*> parms (parms_count);

      if (debug_elaborate) {
	    cerr << get_fileline() << ": PECallFunction::elaborate_base_: "
		 << "Expecting " << parms_count
		 << " argument for function " << scope_path(dscope) << "." << endl;
      }

	/* Elaborate the input expressions for the function. This is
	   done in the scope of the function call, and not the scope
	   of the function being called. The scope of the called
	   function is elaborated when the definition is elaborated. */
      unsigned parm_errors = elaborate_arguments_(des, scope,
						  def, need_const,
						  parms, 0);

      if (need_const && !dscope->is_const_func()) {

              // If this is the first time the function has been called in
              // a constant context, force the function to be re-elaborated.
              // This will generate the necessary error messages to allow
              // the user to diagnose the fault.
            if (!dscope->need_const_func()) {
                  dscope->set_elab_stage(2);
                  dscope->need_const_func(true);
                  const PFunction*pfunc = dscope->func_pform();
                  ivl_assert(*this, pfunc);
                  pfunc->elaborate(des, dscope);
            }

            cerr << get_fileline() << ": error: `" << dscope->basename()
                 << "' is not a constant function." << endl;
            des->errors += 1;
            return 0;
      }

      if (parm_errors)
            return 0;

      if (def->is_void()) {
	    cerr << get_fileline() << ": error: void function `"
		 << dscope->basename() << "` can not be called in an expression."
		 << endl;
	    des->errors++;
	    return nullptr;
      }

	/* Look for the return value signal for the called
	   function. This return value is a magic signal in the scope
	   of the function, that has the name of the function. The
	   function code assigns to this signal to return a value.

	   dscope, in this case, is the scope of the function, so the
	   return value is the name within that scope. */

      if (NetNet*res = dscope->find_signal(dscope->basename())) {
	    NetESignal*eres = new NetESignal(res);
	    NetEUFunc*func = new NetEUFunc(scope, dscope, eres, parms, need_const);
	    func->set_line(*this);
	    return func;
      }

      cerr << get_fileline() << ": internal error: Unable to locate "
              "function return value for " << path_
           << " in " << dscope->basename() << "." << endl;
      des->errors += 1;
      return 0;
}

/*
 * Elaborate the arguments of a function or method. The parms vector
 * is where to place the elaborated expressions, so it an output. The
 * parm_off is where in the parms vector to start writing
 * arguments. This value is normally 0, but is 1 if this is a method
 * so that parms[0] can hold the "this" argument. In this latter case,
 * def->port(0) will be the "this" argument and should be skipped.
 */
unsigned PECallFunction::elaborate_arguments_(Design*des, NetScope*scope,
					      NetFuncDef*def, bool need_const,
					      vector<NetExpr*>&parms,
					      unsigned parm_off) const
{
      unsigned parm_errors = 0;
      unsigned missing_parms = 0;

      const unsigned parm_count = parms.size() - parm_off;
      const unsigned actual_count = parms_.size();

      if (parm_count == 0 && actual_count == 0)
	    return 0;

      if (actual_count > parm_count) {
	    cerr << get_fileline() << ": error: "
		 << "Too many arguments (" << actual_count
		 << ", expecting " << parm_count << ")"
		 << " in call to function." << endl;
	    des->errors += 1;
      }

      auto args = map_named_args(des, def, parms_, parm_off);

      for (unsigned idx = 0 ; idx < parm_count ; idx += 1) {
	    unsigned pidx = idx + parm_off;
	    PExpr *tmp = args[idx];

	    if (tmp) {
		  parms[pidx] = elaborate_rval_expr(des, scope,
						    def->port(pidx)->net_type(),
						    tmp, need_const);
		  if (parms[pidx] == 0) {
			parm_errors += 1;
			continue;
		  }

		  if (NetEEvent*evt = dynamic_cast<NetEEvent*> (parms[pidx])) {
			cerr << evt->get_fileline() << ": error: An event '"
			     << evt->event()->name() << "' can not be a user "
			        "function argument." << endl;
			des->errors += 1;
		  }
		  if (debug_elaborate)
			cerr << get_fileline() << ": debug:"
			     << " function " << path_
			     << " arg " << (idx+1)
			     << " argwid=" << parms[pidx]->expr_width()
			     << ": " << *parms[idx] << endl;

	    } else if (def->port_defe(pidx)) {
		  if (! gn_system_verilog()) {
			cerr << get_fileline() << ": internal error: "
			     << "Found (and using) default function argument "
			     << "requires SystemVerilog." << endl;
			des->errors += 1;
		  }
		  parms[pidx] = def->port_defe(pidx)->dup_expr();

	    } else {
		  missing_parms += 1;
		  parms[pidx] = 0;
	    }
      }

      if (missing_parms > 0) {
	    cerr << get_fileline() << ": error: The function " << path_
		 << " has been called with missing/empty parameters." << endl;
	    cerr << get_fileline() << ":      : Verilog doesn't allow "
		 << "passing empty parameters to functions." << endl;
	    parm_errors += 1;
	    des->errors += 1;
      }

      return parm_errors;
}

/*
 * Look for a method of a given object. The search_results gives us the
 * information we need to look into this case: The net is the object that will
 * have its method applied, and the path_tail is the method we are looking
 * for. The method name is to be interpreted based on the type of the item. So
 * for example if the object is:
 *
 *     <scope>.x.len()
 *
 * Then net refers to object named x, and path_head is "<scope>.x". The method is
 * "len" in path_tail, and if x is a string object, we can handle the case.
 */
NetExpr* PECallFunction::elaborate_expr_method_(Design*des, NetScope*scope,
						symbol_search_results&search_results)
						const
{
      if (!gn_system_verilog()) {
	    cerr << get_fileline() << ": error: "
		 << "Enable SystemVerilog to support object methods." << endl;
	    des->errors += 1;
	    return 0;
      }

      if (search_results.path_tail.size() > 1) {
	    cerr << get_fileline() << ": sorry: "
		 << "Method name nesting is not supported yet." << endl;
	    cerr << get_fileline() << ":      : "
		 << "method path: " << search_results.path_tail << endl;
	    return 0;
      }

      if (debug_elaborate) {
	    cerr << get_fileline() << ": PECallFunction::elaborate_expr_method_: "
		 << "search_results.scope: " << scope_path(search_results.scope) << endl;
	    cerr << get_fileline() << ": PECallFunction::elaborate_expr_method_: "
		 << "search_results.path_head: " << search_results.path_head << endl;
	    cerr << get_fileline() << ": PECallFunction::elaborate_expr_method_: "
		 << "search_results.path_tail: " << search_results.path_tail << endl;
	    if (search_results.net)
		  cerr << get_fileline() << ": PECallFunction::elaborate_expr_method_: "
		       << "search_results.net->data_type: " << search_results.net->data_type() << endl;
	    if (search_results.net && search_results.net->net_type())
		  cerr << get_fileline() << ": PECallFunction::elaborate_expr_method_: "
		       << "search_results.net->net_type: " << *search_results.net->net_type() << endl;
	    if (search_results.par_val)
		  cerr << get_fileline() << ": PECallFunction::elaborate_expr_method_: "
		       << "search_results.par_val: " << *search_results.par_val << endl;
	    if (search_results.type)
		  cerr << get_fileline() << ": PECallFunction::elaborate_expr_method_: "
		       << "search_results.type: " << *search_results.type << endl;
      }

      if (search_results.par_val && search_results.type) {
	    return elaborate_expr_method_par_(des, scope, search_results);
      }

      NetExpr* sub_expr = 0;
      if (search_results.net) {
	    NetESignal*tmp = new NetESignal(search_results.net);
	    tmp->set_line(*this);
	    sub_expr = tmp;
      }

      // Queue variable with a select expression. The type of this expression
      // is the type of the object that will interpret the method. For
      // example:
      //    <scope>.x[e].len()
      // If x is a queue of strings, then x[e] is a string. Elaborate the x[e]
      // expression and pass that to the len() method.
      if (search_results.net && search_results.net->data_type()==IVL_VT_QUEUE
	  && search_results.path_head.back().index.size()==1) {

	    NetNet*net = search_results.net;
	    const netdarray_t*darray = net->darray_type();
	    const index_component_t&use_index = search_results.path_head.back().index.back();
	    ivl_assert(*this, use_index.msb != 0);
	    ivl_assert(*this, use_index.lsb == 0);

	    NetExpr*mux = elab_and_eval(des, scope, use_index.msb, -1, false);
	    if (!mux)
		  return 0;

	    NetESelect*tmp = new NetESelect(sub_expr, mux, darray->element_width(), darray->element_type());
	    tmp->set_line(*this);
	    sub_expr = tmp;
      }

      if (debug_elaborate && sub_expr) {
	    cerr << get_fileline() << ": PECallFunction::elaborate_expr_method_: "
		 << "sub_expr->expr_type: " << sub_expr->expr_type() << endl;
	    if (sub_expr->net_type())
		  cerr << get_fileline() << ": PECallFunction::elaborate_expr_method_: "
		       << "sub_expr->net_type: " << *sub_expr->net_type() << endl;
      }

      ivl_assert(*this, sub_expr);

      // Dynamic array methods. This handles the case that the located signal
      // is a dynamic array, and there is no index.
      if (search_results.net && search_results.net->data_type()==IVL_VT_DARRAY
	  && search_results.path_head.back().index.size()==0) {

	    // Get the method name that we are looking for.
	    perm_string method_name = search_results.path_tail.back().name;

	    if (method_name == "size") {
		  if (parms_.size() != 0) {
			cerr << get_fileline() << ": error: size() method "
			     << "takes no arguments" << endl;
			des->errors += 1;
		  }
		  NetESFunc*sys_expr = new NetESFunc("$size", &netvector_t::atom2u32, 1);
		  sys_expr->set_line(*this);
		  sys_expr->parm(0, sub_expr);
		  return sys_expr;
	    }

	    cerr << get_fileline() << ": error: Method " << method_name
		 << " is not a dynamic array method." << endl;
	    return 0;
      }

      // Queue methods. This handles the case that the located signal is a
      // QUEUE object, and there is a method.
      if (search_results.net && search_results.net->data_type()==IVL_VT_QUEUE
	  && search_results.path_head.back().index.size()==0) {

	    // Get the method name that we are looking for.
	    perm_string method_name = search_results.path_tail.back().name;
	    if (method_name == "size") {
		  if (parms_.size() != 0) {
			cerr << get_fileline() << ": error: size() method "
			     << "takes no arguments" << endl;
			des->errors += 1;
		  }
		  NetESFunc*sys_expr = new NetESFunc("$size", &netvector_t::atom2u32, 1);
		  sys_expr->set_line(*this);
		  sys_expr->parm(0, sub_expr);
		  return sys_expr;
	    }

	    const netqueue_t*queue = search_results.net->queue_type();
	    ivl_type_t element_type = queue->element_type();
	    if (method_name == "pop_back") {
		  if (parms_.size() != 0) {
			cerr << get_fileline() << ": error: pop_back() method "
			     << "takes no arguments" << endl;
			des->errors += 1;
		  }
		  NetESFunc*sys_expr = new NetESFunc("$ivl_queue_method$pop_back",
						     element_type, 1);
		  sys_expr->set_line(*this);
		  sys_expr->parm(0, sub_expr);
		  return sys_expr;
	    }

	    if (method_name == "pop_front") {
		  if (parms_.size() != 0) {
			cerr << get_fileline() << ": error: pop_front() method "
			     << "takes no arguments" << endl;
			des->errors += 1;
		  }
		  NetESFunc*sys_expr = new NetESFunc("$ivl_queue_method$pop_front",
						     element_type, 1);
		  sys_expr->set_line(*this);
		  sys_expr->parm(0, sub_expr);
		  return sys_expr;
	    }

	    cerr << get_fileline() << ": error: Method " << method_name
		 << " is not a queue method." << endl;
	    des->errors += 1;
	    return 0;
      }

      // Enumeration methods.
      if (search_results.net && search_results.net->enumeration()) {

	    NetNet*net = search_results.net;
	    const netenum_t*netenum = net->enumeration();

	    // Get the method name that we are looking for.
	    perm_string method_name = search_results.path_tail.back().name;
	    return check_for_enum_methods(this, des, scope,
					  netenum, path_,
					  method_name, sub_expr,
					  parms_);
      }

      // Class methods. Generate function call to the class method.
      if (sub_expr->expr_type()==IVL_VT_CLASS) {

	    // Get the method name that we are looking for.
	    perm_string method_name = search_results.path_tail.back().name;

	    NetNet*net = search_results.net;
	    const netclass_t*class_type = dynamic_cast<const netclass_t*>(search_results.type);
	    ivl_assert(*this, class_type);
	    NetScope*method = class_type->method_from_name(method_name);

	    if (method == 0) {
		  cerr << get_fileline() << ": Error: " << method_name
		       << " is not a method of class " << class_type->get_name()
		       << "." << endl;
		  des->errors += 1;
		  return 0;
	    }

	    NetFuncDef*def = method->func_def();
	    ivl_assert(*this, def);

	    NetNet*res = method->find_signal(method->basename());
	    ivl_assert(*this, res);

	    vector<NetExpr*> parms(def->port_count());
	    ivl_assert(*this, def->port_count() >= 1);

	    NetESignal*ethis = new NetESignal(net);
	    ethis->set_line(*this);
	    parms[0] = ethis;

	    elaborate_arguments_(des, scope, def, false, parms, 1);

	    NetESignal*eres = new NetESignal(res);
	    NetEUFunc*call = new NetEUFunc(scope, method, eres, parms, false);
	    call->set_line(*this);
	    return call;
      }

      // String methods.
      if (sub_expr->expr_type()==IVL_VT_STRING) {

	    // Get the method name that we are looking for.
	    perm_string method_name = search_results.path_tail.back().name;

	    if (method_name == "len") {
		  NetESFunc*sys_expr = new NetESFunc("$ivl_string_method$len",
						     &netvector_t::atom2u32, 1);
		  sys_expr->parm(0, sub_expr);
		  return sys_expr;
	    }

	    if (method_name == "atoi") {
		  NetESFunc*sys_expr = new NetESFunc("$ivl_string_method$atoi",
						     netvector_t::integer_type(), 1);
		  sys_expr->parm(0, sub_expr);
		  return sys_expr;
	    }

	    if (method_name == "atoreal") {
		  NetESFunc*sys_expr = new NetESFunc("$ivl_string_method$atoreal",
						     &netreal_t::type_real, 1);
		  sys_expr->parm(0, sub_expr);
		  return sys_expr;
	    }

	    if (method_name == "atohex") {
		  NetESFunc*sys_expr = new NetESFunc("$ivl_string_method$atohex",
						     netvector_t::integer_type(), 1);
		  sys_expr->parm(0, sub_expr);
		  return sys_expr;
	    }

	    if (method_name == "substr") {
		  if (parms_.size() != 2)
			cerr << get_fileline() << ": error: Method `substr()`"
			     << " requires 2 arguments, got " << parms_.size()
			     << "." << endl;

		  static const std::vector<perm_string> parm_names = {
			perm_string::literal("i"),
			perm_string::literal("j")
		  };
		  auto args = map_named_args(des, parm_names, parms_);

		  NetESFunc*sys_expr = new NetESFunc("$ivl_string_method$substr",
						     &netstring_t::type_string, 3);
		  sys_expr->set_line(*this);

		    // First argument is the source string.
		  sys_expr->parm(0, sub_expr);

		  for (int i = 0; i < 2; i++) {
			if (!args[i])
			      continue;

			auto expr = elaborate_rval_expr(des, scope,
						        &netvector_t::atom2u32,
						        args[i], false);
			sys_expr->parm(i + 1, expr);
		  }

		  return sys_expr;
	    }

	    cerr << get_fileline() << ": error: Method " << method_name
		 << " is not a string method." << endl;
	    return 0;
      }

      return 0;
}

/*
 * Handle parameters differently because some must constant elimination is
 * possible here. We know by definition that the par_val is a constant
 * expression of some sort (it's a parameter value) and most methods are
 * stable in the sense that they generate a constant value for a constant input.
 */
NetExpr* PECallFunction::elaborate_expr_method_par_(Design*des, NetScope*scope,
						    symbol_search_results&search_results)
						    const
{
      ivl_assert(*this, search_results.par_val);
      ivl_assert(*this, search_results.type);

      const NetExpr*par_val = search_results.par_val;
      ivl_type_t par_type = search_results.type;
      perm_string method_name = search_results.path_tail.back().name;

      // If the parameter is of type string, then look for the standard string
      // methods. Return an error if not found. Since we are assured that the
      // expression is a constant string, it should be able to calculate the
      // result at compile time.
      if (dynamic_cast<const netstring_t*>(par_type)) {

	    const NetECString*par_string = dynamic_cast<const NetECString*>(par_val);
	    ivl_assert(*par_val, par_string);
	    string par_value = par_string->value().as_string();

	    if (method_name=="len") {
		  NetEConst*use_val = make_const_val(par_value.size());
		  use_val->set_line(*this);
		  return use_val;
	    }

	    if (method_name == "atoi") {
		  NetEConst*use_val = make_const_val(atoi(par_value.c_str()));
		  use_val->set_line(*this);
		  return use_val;
	    }

	    if (method_name == "atoreal") {
		  NetECReal*use_val = new NetECReal(verireal(par_value.c_str()));
		  use_val->set_line(*this);
		  return use_val;
	    }

	    if (method_name == "atohex") {
		  NetEConst*use_val = make_const_val(strtoul(par_value.c_str(),0,16));
		  use_val->set_line(*this);
		  return use_val;
	    }

	    // Returning 0 here will cause the caller to print an error
	    // message and increment the error count, so there is no need to
	    // increment des->error_count here.
	    cerr << get_fileline() << ": error: "
		 << "Unknown or unsupport string method: " << method_name
		 << endl;
	    return 0;
      }

      // If we haven't figured out what to do with this method by now,
      // something went wrong.
      cerr << get_fileline() << ": sorry: Don't know how to handle methods of parameters of type:" << endl;
      cerr << get_fileline() << ":      : " << *par_type << endl;
      cerr << get_fileline() << ":      : in scope " << scope_path(scope) << endl;

      des->errors += 1;
      return 0;
}

unsigned PECastSize::test_width(Design*des, NetScope*scope, width_mode_t&)
{
      ivl_assert(*this, size_);
      ivl_assert(*this, base_);

      expr_width_ = 0;

      NetExpr*size_ex = elab_and_eval(des, scope, size_, -1, true);
      NetEConst*size_ce = dynamic_cast<NetEConst*>(size_ex);
      if (size_ce && !size_ce->value().is_negative())
	    expr_width_ = size_ce->value().as_ulong();
      delete size_ex;
      if (expr_width_ == 0) {
	    cerr << get_fileline() << ": error: Cast size expression "
		    "must be constant and greater than zero." << endl;
	    des->errors += 1;
	    return 0;
      }

      width_mode_t tmp_mode = PExpr::SIZED;
      base_->test_width(des, scope, tmp_mode);

      if (!type_is_vectorable(base_->expr_type())) {
	    cerr << get_fileline() << ": error: Cast base expression "
		    "must be a vector type." << endl;
	    des->errors += 1;
	    return 0;
      }

      expr_type_   = base_->expr_type();
      min_width_   = expr_width_;
      signed_flag_ = base_->has_sign();

      return expr_width_;
}

NetExpr* PECastSize::elaborate_expr(Design*des, NetScope*scope,
				    unsigned expr_wid, unsigned flags) const
{
      flags &= ~SYS_TASK_ARG; // don't propagate the SYS_TASK_ARG flag

      ivl_assert(*this, size_);
      ivl_assert(*this, base_);

	// A cast behaves exactly like an assignment to a temporary variable,
	// so the temporary result size may affect the sub-expression width.
      unsigned cast_width = base_->expr_width();
      if (cast_width < expr_width_)
            cast_width = expr_width_;

      NetExpr*sub = base_->elaborate_expr(des, scope, cast_width, flags);
      if (sub == 0)
	    return 0;

	// Perform the cast. The extension method (zero/sign), if needed,
	// depends on the type of the base expression.
      NetExpr*tmp = cast_to_width(sub, expr_width_, base_->has_sign(), *this);

	// Pad up to the expression width. The extension method (zero/sign)
	// depends on the type of enclosing expression.
      return pad_to_width(tmp, expr_wid, signed_flag_, *this);
}

unsigned PECastType::test_width(Design*des, NetScope*scope, width_mode_t&)
{
      target_type_ = target_->elaborate_type(des, scope);

      width_mode_t tmp_mode = PExpr::SIZED;
      base_->test_width(des, scope, tmp_mode);

      if (const netdarray_t*use_darray = dynamic_cast<const netdarray_t*>(target_type_)) {
	    expr_type_  = use_darray->element_base_type();
	    expr_width_ = use_darray->element_width();

      } else if (const netstring_t*use_string = dynamic_cast<const netstring_t*>(target_type_)) {
	    expr_type_  = use_string->base_type();
	    expr_width_ = 8;

      } else {
	    expr_type_  = target_type_->base_type();
	    expr_width_ = target_type_->packed_width();
      }
      min_width_   = expr_width_;
      signed_flag_ = target_type_->get_signed();

      return expr_width_;
}

NetExpr* PECastType::elaborate_expr(Design*des, NetScope*scope,
                                    ivl_type_t type, unsigned flags) const
{
    const netdarray_t*darray = NULL;
    const netvector_t*vector = NULL;

    // Casting array of vectors to dynamic array type
    if((darray = dynamic_cast<const netdarray_t*>(type)) &&
            (vector = dynamic_cast<const netvector_t*>(darray->element_type()))) {
        PExpr::width_mode_t mode = PExpr::SIZED;
        unsigned use_wid = base_->test_width(des, scope, mode);
        NetExpr*base = base_->elaborate_expr(des, scope, use_wid, NO_FLAGS);

        ivl_assert(*this, vector->packed_width() > 0);
        ivl_assert(*this, base->expr_width() > 0);

        // Find rounded up length that can fit the whole casted array of vectors
        int len = base->expr_width() + vector->packed_width() - 1;
        if(base->expr_width() > (unsigned)vector->packed_width()) {
            len /= vector->packed_width();
        } else {
            len /= base->expr_width();
        }

        // Number of words in the created dynamic array
        NetEConst*len_expr = new NetEConst(verinum(len));
        return new NetENew(type, len_expr, base);
    }

    // Fallback
    return elaborate_expr(des, scope, (unsigned) 0, flags);
}

NetExpr* PECastType::elaborate_expr(Design*des, NetScope*scope,
				    unsigned expr_wid, unsigned flags) const
{
      flags &= ~SYS_TASK_ARG; // don't propagate the SYS_TASK_ARG flag

	// A cast behaves exactly like an assignment to a temporary variable,
	// so the temporary result size may affect the sub-expression width.
      unsigned cast_width = base_->expr_width();
      if (type_is_vectorable(base_->expr_type()) && (cast_width < expr_width_))
	    cast_width = expr_width_;

      NetExpr*sub = base_->elaborate_expr(des, scope, cast_width, flags);
      if (sub == 0)
	    return 0;

      NetExpr*tmp = 0;
      if (dynamic_cast<const netreal_t*>(target_type_)) {
	    return cast_to_real(sub);
      } else if (dynamic_cast<const netstring_t*>(target_type_)) {
	    if (base_->expr_type() == IVL_VT_STRING)
		  return sub; // no conversion
	    if (base_->expr_type() == IVL_VT_LOGIC ||
		base_->expr_type() == IVL_VT_BOOL)
		  return sub; // handled by the target as special cases
      } else if (target_type_ && target_type_->packed()) {
	    switch (target_type_->base_type()) {
		case IVL_VT_BOOL:
		  tmp = cast_to_int2(sub, expr_width_);
		  break;

		case IVL_VT_LOGIC:
		  tmp = cast_to_int4(sub, expr_width_);
		  break;

		default:
		  break;
	    }
      }
      if (tmp) {
	    if (tmp == sub) {
		    // We already had the correct base type, so we just need to
		    // fix the size. Note that even if the size is already correct,
                    // we still need to isolate the sub-expression from changes in
                    // the signedness pushed down from the main expression.
		  tmp = cast_to_width(sub, expr_width_, sub->has_sign(), *this);
	    }
	    return pad_to_width(tmp, expr_wid, signed_flag_, *this, target_type_);
      }

      cerr << get_fileline() << ": sorry: This cast operation is not yet supported." << endl;
      des->errors += 1;
      return 0;
}

unsigned PECastSign::test_width(Design *des, NetScope *scope, width_mode_t &mode)
{
      ivl_assert(*this, base_);

      expr_width_ = sign_cast_width(des, scope, *base_, mode);
      expr_type_  = base_->expr_type();
      min_width_  = base_->min_width();

      if (!type_is_vectorable(base_->expr_type())) {
	    cerr << get_fileline() << ": error: Cast base expression "
		    "must be a vector type." << endl;
	    des->errors += 1;
	    return 0;
      }

      return expr_width_;
}

NetExpr* PECastSign::elaborate_expr(Design *des, NetScope *scope,
				    unsigned expr_wid, unsigned flags) const
{
      ivl_assert(*this, base_);

      flags &= ~SYS_TASK_ARG; // don't propagate the SYS_TASK_ARG flag

      NetExpr *sub = base_->elaborate_expr(des, scope, expr_width_, flags);
      if (!sub)
	    return nullptr;

      return cast_to_width(sub, expr_wid, signed_flag_, *this);
}

unsigned PEConcat::test_width(Design*des, NetScope*scope, width_mode_t&)
{
      expr_width_ = 0;
      enum {NO, MAYBE, YES} expr_is_string = MAYBE;
      for (unsigned idx = 0 ; idx < parms_.size() ; idx += 1) {
	      // Add in the width of this sub-expression.
	    expr_width_ += parms_[idx]->test_width(des, scope, width_modes_[idx]);

	      // If we already know this is not a string, then move on.
	    if (expr_is_string == NO)
		  continue;

	      // If this expression is a string, then the
	      // concatenation is a string until we find a reason to
	      // deny it.
	    if (parms_[idx]->expr_type()==IVL_VT_STRING) {
		  expr_is_string = YES;
		  continue;
	    }

	      // If this is a string literal, then this may yet be a string.
	    if (dynamic_cast<PEString*> (parms_[idx]))
		  continue;

	      // Failed to allow a string result.
	    expr_is_string = NO;
      }

      expr_type_   = (expr_is_string==YES) ? IVL_VT_STRING : IVL_VT_LOGIC;
      signed_flag_ = false;

	// If there is a repeat expression, then evaluate the constant
	// value and set the repeat count.
      if (repeat_ && (scope != tested_scope_)) {
	    NetExpr*tmp = elab_and_eval(des, scope, repeat_, -1, true);
	    if (tmp == 0) return 0;

	    if (tmp->expr_type() == IVL_VT_REAL) {
		  cerr << tmp->get_fileline() << ": error: Concatenation "
		       << "repeat expression can not be REAL." << endl;
		  des->errors += 1;
		  return 0;
	    }

	    NetEConst*rep = dynamic_cast<NetEConst*>(tmp);

	    if (rep == 0) {
		  cerr << get_fileline() << ": error: "
			"Concatenation repeat expression is not constant."
		       << endl;
		  cerr << get_fileline() << ":      : The expression is: "
		       << *tmp << endl;
		  des->errors += 1;
		  return 0;
	    }

	    if (!rep->value().is_defined()) {
		  cerr << get_fileline() << ": error: Concatenation repeat "
		       << "may not be undefined (" << rep->value()
		       << ")." << endl;
		  des->errors += 1;
		  return 0;
	    }

	    if (rep->value().is_negative()) {
		  cerr << get_fileline() << ": error: Concatenation repeat "
		       << "may not be negative (" << rep->value().as_long()
		       << ")." << endl;
		  des->errors += 1;
		  return 0;
	    }

            repeat_count_ = rep->value().as_ulong();

            tested_scope_ = scope;
      }
      expr_width_ *= repeat_count_;
      min_width_   = expr_width_;

      return expr_width_;
}

// Keep track of the concatenation/repeat depth.
static int concat_depth = 0;

NetExpr* PEConcat::elaborate_expr(Design*des, NetScope*scope,
				  ivl_type_t ntype, unsigned flags) const
{
      switch (ntype->base_type()) {
	  case IVL_VT_QUEUE:
// FIXME: Does a DARRAY support a zero size?
	  case IVL_VT_DARRAY:
	    if (parms_.size() == 0) {
		  NetENull*tmp = new NetENull;
		  tmp->set_line(*this);
		  return tmp;
	    } else {
		  const netdarray_t*array_type = dynamic_cast<const netdarray_t*> (ntype);
		  ivl_assert(*this, array_type);

		    // This is going to be an array pattern, so run through the
		    // elements of the expression and elaborate each as if they
		    // are element_type expressions.
		  ivl_type_t elem_type = array_type->element_type();
		  vector<NetExpr*> elem_exprs (parms_.size());
		  for (size_t idx = 0 ; idx < parms_.size() ; idx += 1) {
			NetExpr*tmp = parms_[idx]->elaborate_expr(des, scope, elem_type, flags);
			elem_exprs[idx] = tmp;
		  }

		  NetEArrayPattern*res = new NetEArrayPattern(array_type, elem_exprs);
		  res->set_line(*this);
		  return res;
	    }
	  default:
	    cerr << get_fileline() << ": internal error: "
		 << "I don't know how to elaborate(ivl_type_t)"
		 << " this expression: " << *this << endl;
	    return 0;
      }
}

NetExpr* PEConcat::elaborate_expr(Design*des, NetScope*scope,
				  unsigned expr_wid, unsigned flags) const
{
      flags &= ~SYS_TASK_ARG; // don't propagate the SYS_TASK_ARG flag

      concat_depth += 1;

      if (debug_elaborate) {
	    cerr << get_fileline() << ": debug: Elaborate expr=" << *this
		 << ", expr_wid=" << expr_wid << endl;
      }

      if (repeat_count_ == 0 && concat_depth < 2) {
            cerr << get_fileline() << ": error: Concatenation repeat "
                 << "may not be zero in this context." << endl;
            des->errors += 1;
            concat_depth -= 1;
            return 0;
      }

      unsigned wid_sum = 0;
      unsigned parm_cnt = 0;
      unsigned parm_errors = 0;
      std::vector<NetExpr*> parms(parms_.size());

	/* Elaborate all the parameters and attach them to the concat node. */
      for (unsigned idx = 0 ;  idx < parms_.size() ;  idx += 1) {
	    if (parms_[idx] == 0) {
		  cerr << get_fileline() << ": error: Missing expression "
		       << (idx+1) << " of concatenation list." << endl;
		  des->errors += 1;
		  continue;
	    }

	    ivl_assert(*this, parms_[idx]);
            unsigned wid = parms_[idx]->expr_width();
	    NetExpr*ex = parms_[idx]->elaborate_expr(des, scope, wid, flags);
	    if (ex == 0) continue;

	    ex->set_line(*parms_[idx]);

            eval_expr(ex, -1);

	    if (ex->expr_type() == IVL_VT_REAL) {
		  cerr << ex->get_fileline() << ": error: "
		       << "Concatenation operand can not be real: "
		       << *parms_[idx] << endl;
		  des->errors += 1;
                  parm_errors += 1;
		  continue;
	    }

	    if (width_modes_[idx] != SIZED) {
		  cerr << ex->get_fileline() << ": error: "
		       << "Concatenation operand \"" << *parms_[idx]
		       << "\" has indefinite width." << endl;
		  des->errors += 1;
                  parm_errors += 1;
		  continue;
	    }

	      /* We are going to ignore zero width constants. */
	    if ((ex->expr_width() == 0) && dynamic_cast<NetEConst*>(ex)) {
		  parms[idx] = 0;
	    } else {
		  parms[idx] = ex;
		  parm_cnt += 1;
	    }
	    wid_sum += ex->expr_width();
      }
      if (parm_errors) {
	    concat_depth -= 1;
	    return 0;
      }

	/* Make the empty concat expression. */
      NetEConcat*cncat = new NetEConcat(parm_cnt, repeat_count_, expr_type_);
      cncat->set_line(*this);

	/* Remove any zero width constants. */
      unsigned off = 0;
      for (unsigned idx = 0 ;  idx < parm_cnt ;  idx += 1) {
	    while (parms[off+idx] == 0) off += 1;
	    cncat->set(idx, parms[off+idx]);
      }

      if (wid_sum == 0 && expr_type_ != IVL_VT_STRING) {
	    cerr << get_fileline() << ": error: Concatenation/replication "
	         << "may not have zero width in this context." << endl;
	    des->errors += 1;
	    concat_depth -= 1;
	    delete cncat;
	    return 0;
      }

      NetExpr*tmp = pad_to_width(cncat, expr_wid, signed_flag_, *this);

      concat_depth -= 1;
      return tmp;
}

/*
 * Floating point literals are not vectorable. It's not particularly
 * clear what to do about an actual width to return, but whatever the
 * width, it is unsigned.
 *
 * Absent any better idea, we call all real valued results a width of 1.
 */
unsigned PEFNumber::test_width(Design*, NetScope*, width_mode_t&)
{
      expr_type_   = IVL_VT_REAL;
      expr_width_  = 1;
      min_width_   = 1;
      signed_flag_ = true;

      return expr_width_;
}

NetExpr* PEFNumber::elaborate_expr(Design*, NetScope*, ivl_type_t, unsigned) const
{
      NetECReal*tmp = new NetECReal(*value_);
      tmp->set_line(*this);
      return tmp;
}

NetExpr* PEFNumber::elaborate_expr(Design*, NetScope*, unsigned, unsigned) const
{
      NetECReal*tmp = new NetECReal(*value_);
      tmp->set_line(*this);
      return tmp;
}

bool PEIdent::calculate_packed_indices_(Design*des, NetScope*scope, NetNet*net,
					list<long>&prefix_indices) const
{
      unsigned dimensions = net->unpacked_dimensions() + net->packed_dimensions();
      switch (net->data_type()) {
	  case IVL_VT_STRING:
	  case IVL_VT_DARRAY:
	  case IVL_VT_QUEUE:
	    dimensions += 1;
	  default:
	    break;
      }
      if (path_.back().index.size() > dimensions) {
	    cerr << get_fileline() << ": error: the number of indices ("
		 << path_.back().index.size()
		 << ") is greater than the number of dimensions ("
		 << dimensions
		 << ")." << endl;
	    des->errors += 1;
	    return false;
      }

      list<index_component_t> index;
      index = path_.back().index;
      ivl_assert(*this, index.size() >= net->unpacked_dimensions());
      for (size_t idx = 0 ; idx < net->unpacked_dimensions() ; idx += 1)
	    index.pop_front();

      return evaluate_index_prefix(des, scope, prefix_indices, index);
}


bool PEIdent::calculate_bits_(Design*des, NetScope*scope,
			      long&msb, bool&defined) const
{
      defined = true;
      const name_component_t&name_tail = path_.back();
      ivl_assert(*this, !name_tail.index.empty());

      const index_component_t&index_tail = name_tail.index.back();
      ivl_assert(*this, index_tail.sel == index_component_t::SEL_BIT);
      ivl_assert(*this, index_tail.msb && !index_tail.lsb);

	/* This handles bit selects. In this case, there in one
	   bit select expressions which must be constant. */

      NetExpr*msb_ex = elab_and_eval(des, scope, index_tail.msb, -1, true);
      NetEConst*msb_c = dynamic_cast<NetEConst*>(msb_ex);
      if (msb_c == 0) {
	    cerr << index_tail.msb->get_fileline() << ": error: "
	            "Bit select expressions must be a constant integral value."
	         << endl;
	    cerr << index_tail.msb->get_fileline() << ":      : "
	            "This expression violates that rule: "
	         << *index_tail.msb << endl;
	    des->errors += 1;
              /* Attempt to recover from error. */
            msb = 0;
      } else {
	    if (! msb_c->value().is_defined())
		  defined = false;
            msb = msb_c->value().as_long();
      }

      delete msb_ex;
      return true;
}

/*
 * Given that the msb_ and lsb_ are part select expressions, this
 * function calculates their values. Note that this method does *not*
 * convert the values to canonical form.
 */
bool PEIdent::calculate_parts_(Design*des, NetScope*scope,
			       long&msb, long&lsb, bool&defined) const
{
      defined = true;
      const name_component_t&name_tail = path_.back();
      ivl_assert(*this, !name_tail.index.empty());

      const index_component_t&index_tail = name_tail.index.back();
      ivl_assert(*this, index_tail.sel == index_component_t::SEL_PART);
      ivl_assert(*this, index_tail.msb && index_tail.lsb);

	/* This handles part selects. In this case, there are
	   two bit select expressions, and both must be
	   constant. Evaluate them and pass the results back to
	   the caller. */
      NetExpr*lsb_ex = elab_and_eval(des, scope, index_tail.lsb, -1, true);
      NetEConst*lsb_c = dynamic_cast<NetEConst*>(lsb_ex);
      if (lsb_c == 0) {
	    cerr << index_tail.lsb->get_fileline() << ": error: "
	            "Part select expressions must be constant integral values."
	         << endl;
	    cerr << index_tail.lsb->get_fileline() << ":      : "
	            "The lsb expression violates that rule: "
	         << *index_tail.lsb << endl;
	    des->errors += 1;
              /* Attempt to recover from error. */
            lsb = 0;
      } else {
	    if (! lsb_c->value().is_defined())
		  defined = false;
            lsb = lsb_c->value().as_long();
      }

      NetExpr*msb_ex = elab_and_eval(des, scope, index_tail.msb, -1, true);
      NetEConst*msb_c = dynamic_cast<NetEConst*>(msb_ex);
      if (msb_c == 0) {
	    cerr << index_tail.msb->get_fileline() << ": error: "
	            "Part select expressions must be constant integral values."
	         << endl;
	    cerr << index_tail.msb->get_fileline() << ":      : "
	            "The msb expression violates that rule: "
	         << *index_tail.msb << endl;
	    des->errors += 1;
              /* Attempt to recover from error. */
            msb = lsb;
      } else {
	    if (! msb_c->value().is_defined())
		  defined = false;
            msb = msb_c->value().as_long();
      }

      delete msb_ex;
      delete lsb_ex;
      return true;
}

bool PEIdent::calculate_up_do_width_(Design*des, NetScope*scope,
				     unsigned long&wid) const
{
      const name_component_t&name_tail = path_.back();
      ivl_assert(*this, !name_tail.index.empty());

      const index_component_t&index_tail = name_tail.index.back();
      ivl_assert(*this, index_tail.lsb && index_tail.msb);

      bool flag = true;

	/* Calculate the width expression (in the lsb_ position)
	   first. If the expression is not constant, error but guess 1
	   so we can keep going and find more errors. */
      NetExpr*wid_ex = elab_and_eval(des, scope, index_tail.lsb, -1, true);
      NetEConst*wid_c = dynamic_cast<NetEConst*>(wid_ex);

      wid = wid_c ? wid_c->value().as_ulong() : 0;
      if (wid == 0) {
	    cerr << index_tail.lsb->get_fileline() << ": error: "
		  "Indexed part select width must be an integral constants greater than zero."
		 << endl;
	    cerr << index_tail.lsb->get_fileline() << ":      : "
		  "This width expression violates that rule: "
		 << *index_tail.lsb << endl;
	    des->errors += 1;
	    flag = false;
	    wid = 1;
      }
      delete wid_ex;

      return flag;
}

/*
 * When we know that this is an indexed part select (up or down) this
 * method calculates the up/down base, as far at it can be calculated.
 */
NetExpr* PEIdent::calculate_up_do_base_(Design*des, NetScope*scope,
                                        bool need_const) const
{
      const name_component_t&name_tail = path_.back();
      ivl_assert(*this, !name_tail.index.empty());

      const index_component_t&index_tail = name_tail.index.back();
      ivl_assert(*this, index_tail.lsb != 0);
      ivl_assert(*this, index_tail.msb != 0);

      NetExpr*tmp = elab_and_eval(des, scope, index_tail.msb, -1, need_const);
      return tmp;
}

unsigned PEIdent::test_width_parameter_(const NetExpr *par, width_mode_t&mode)
{
	// The width of an enumeration literal is the width of the
	// enumeration base.
      if (const NetEConstEnum*par_enum = dynamic_cast<const NetEConstEnum*> (par)) {
	    const netenum_t*use_enum = par_enum->enumeration();
	    ivl_assert(*this, use_enum != 0);

	    expr_type_   = use_enum->base_type();
	    expr_width_  = use_enum->packed_width();
	    min_width_   = expr_width_;
	    signed_flag_ = par_enum->has_sign();

	    return expr_width_;
      }

      expr_type_   = par->expr_type();
      expr_width_  = par->expr_width();
      min_width_   = expr_width_;
      signed_flag_ = par->has_sign();

      if (!par->has_width() && (mode < LOSSLESS))
	    mode = LOSSLESS;

      return expr_width_;
}

ivl_type_t PEIdent::resolve_type_(Design *des, const symbol_search_results &sr,
				  unsigned int &index_depth) const
{
      ivl_type_t type;
      if (sr.net && sr.net->unpacked_dimensions())
	    type = sr.net->array_type();
      else
	    type = sr.type;

      auto path = sr.path_tail.cbegin();

      ivl_assert(*this, !sr.path_head.empty());

      // Start with processing the indices of the path head
      auto indices = &sr.path_head.back().index;

      while (type) {
	    auto index = indices->cbegin();
	    index_depth = indices->size();

	    // First process all indices
	    while (index_depth) {
		  if (type == &netstring_t::type_string) {
			index++;
			index_depth--;
			type = &netvector_t::atom2u8;
		  } else if (auto array = dynamic_cast<const netsarray_t*>(type)) {
			auto array_size = array->static_dimensions().size();

			// Not enough indices to consume the array
			if (index_depth < array_size)
			      return type;

			index_depth -= array_size;
			while (array_size--)
			      index++;

			type = array->element_type();
		  } else if (auto darray = dynamic_cast<const netdarray_t*>(type)) {
			index++;
			index_depth--;
			type = darray->element_type();
		  } else {
			return type;
		  }
	    }

	    if (path == sr.path_tail.cend())
		  return type;

	    // Next look up the next path element based on name

	    const auto &name = path->name;

	    if (auto class_type = dynamic_cast<const netclass_t*>(type)) {
		  // If the type is an object, the next path member may be a
		  // class property.
		  ivl_type_t par_type;
		  if (class_type->get_parameter(des, name, par_type)) {
			type = par_type;
		  } else {
			int pidx = class_type->property_idx_from_name(name);
			if (pidx < 0)
			      return nullptr;

			type = class_type->get_prop_type(pidx);
		  }
	    } else if (auto struct_type = dynamic_cast<const netstruct_t*>(type)) {
		  // If this net is a struct, the next path element may be a
		  // struct member. If it is, then we know the type of this
		  // identifier by knowing the type of the member.
		  if (debug_elaborate) {
			cerr << get_fileline() << ": debug: PEIdent::test_width: "
			     << "Element is a struct, "
			     << "checking width of member " << name << endl;
		  }

		  unsigned long unused;
		  auto mem = struct_type->packed_member(name, unused);
		  if (!mem)
			return nullptr;

		  type = mem->net_type;
	    } else if (auto queue = dynamic_cast<const netqueue_t*>(type)) {
		  if (name == "size")
			type = &netvector_t::atom2s32;
		  else if (name == "pop_back" || name == "pop_front")
			type = queue->element_type();
		  else
			return nullptr;
	    } else if (dynamic_cast<const netdarray_t*>(type)) {
		  if (name == "size")
			type = &netvector_t::atom2s32;
		  else
			return nullptr;
	    } else if (auto netenum = dynamic_cast<const netenum_t*>(type)) {
		  if (name == "num")
			type = &netvector_t::atom2s32;
		  else if ((name == "first") || (name == "last") ||
			   (name == "next") || (name == "prev"))
			type = netenum;
		  else
			return nullptr;
	    } else {
		  // Type has no members, properties or functions. Path is
		  // invalid.
		  return nullptr;
	    }

	    indices = &path->index;
	    path++;
      }

      return type;
}

unsigned PEIdent::test_width(Design*des, NetScope*scope, width_mode_t&mode)
{
      symbol_search_results sr;
      bool found_symbol = symbol_search(this, des, scope, path_, lexical_pos_, &sr);

	// If there is a part/bit select expression, then process it
	// here. This constrains the results no matter what kind the
	// name is.

      const name_component_t&name_tail = path_.back();
      index_component_t::ctype_t use_sel = index_component_t::SEL_NONE;
      if (!name_tail.index.empty()) {
	    const index_component_t&index_tail = name_tail.index.back();
	    use_sel = index_tail.sel;
      }

      unsigned use_width = UINT_MAX;
      switch (use_sel) {
	  case index_component_t::SEL_NONE:
	    break;
	  case index_component_t::SEL_PART:
	      { long msb, lsb;
		bool parts_defined;
		calculate_parts_(des, scope, msb, lsb, parts_defined);
		if (parts_defined)
		      use_width = 1 + ((msb>lsb) ? (msb-lsb) : (lsb-msb));
		else
		      use_width = UINT_MAX;
		break;
	      }
	  case index_component_t::SEL_IDX_UP:
	  case index_component_t::SEL_IDX_DO:
	      { unsigned long tmp = 0;
		calculate_up_do_width_(des, scope, tmp);
		use_width = tmp;
		break;
	      }
	  case index_component_t::SEL_BIT:
	      { ivl_assert(*this, !name_tail.index.empty());
		const index_component_t&index_tail = name_tail.index.back();
		ivl_assert(*this, index_tail.msb);
	      }
	      use_width = 1;
	      break;
	  case index_component_t::SEL_BIT_LAST:
	    if (debug_elaborate) {
		  cerr << get_fileline() << ": PEIdent::test_width: "
		       << "Queue/Darray last index ($)" << endl;
	    }
	    break;
	  default:
	    ivl_assert(*this, 0);
      }

      unsigned int use_depth = path_.back().index.size();
      ivl_type_t type = nullptr;

      if (found_symbol)
	    type = resolve_type_(des, sr, use_depth);

      if (use_width != UINT_MAX && (!type || (use_depth != 0 && type->packed()))) {
	      // We have a bit/part select. Account for any remaining dimensions
	      // beyond the indexed dimension.
	    if (type) {
		  const auto &slice_dims = type->slice_dimensions();
		  for ( ; use_depth < slice_dims.size(); use_depth++)
			use_width *= slice_dims[use_depth].width();
	    }

	    expr_type_   = IVL_VT_LOGIC; // Assume bit/parts selects are logic
	    expr_width_  = use_width;
	    min_width_   = use_width;
            signed_flag_ = false;

	    return expr_width_;
      }

      // The width of a parameter is the width of the parameter value
      // (as evaluated earlier).
      if (sr.par_val != 0)
	    return test_width_parameter_(sr.par_val, mode);

      // If the identifier has a type take the information from the type
      if (type) {
	      // Unindexed indentifier
	    if (use_width == UINT_MAX)
		  use_width = 1;

	    // In this case, we have an unpacked array or a slice of an
	    // unpacked array. These expressions strictly speaking do
	    // not have a width. But we use the value calculated here
	    // for things $bits(), so return the full number of bits of
	    // the expression.
	    while (auto uarray = dynamic_cast<const netuarray_t *>(type)) {
		  const auto &dims = uarray->static_dimensions();
		  for ( ; use_depth < dims.size(); use_depth++)
			use_width *= dims[use_depth].width();

		  type = uarray->element_type();
		  use_depth = 0;
	    }

	    const auto &slice_dims = type->slice_dimensions();
	    for ( ; use_depth < slice_dims.size(); use_depth++)
		  use_width *= slice_dims[use_depth].width();

	    expr_type_   = type->base_type();
	    expr_width_  = use_width;
	    min_width_   = expr_width_;
	    signed_flag_ = type->get_signed();

	    if (debug_elaborate) {
		  cerr << get_fileline() << ": PEIdent::test_width: "
		       << path_
		       << ", type=" << expr_type_
		       << ", width=" << expr_width_
		       << ", signed_=" << (signed_flag_ ? "true" : "false")
		       << ", use_depth=" << use_depth
		       << endl;
	    }
	    return expr_width_;
      }

      if (path_.size() == 1
	  && scope->genvar_tmp.str()
	  && strcmp(peek_tail_name(path_), scope->genvar_tmp) == 0) {
	    verinum val (scope->genvar_tmp_val);
            expr_type_   = IVL_VT_BOOL;
            expr_width_  = val.len();
            min_width_   = expr_width_;
            signed_flag_ = true;

            if (gn_strict_expr_width_flag) {
                  expr_width_ = integer_width;
                  mode = UNSIZED;
            } else if (mode < LOSSLESS) {
                  mode = LOSSLESS;
            }

            return expr_width_;
      }

	// Not a net, and not a parameter? Give up on the type, but
	// set the width to 0.
      expr_type_   = IVL_VT_NO_TYPE;
      expr_width_  = 0;
      min_width_   = 0;
      signed_flag_ = false;

      return expr_width_;
}


NetExpr* PEIdent::elaborate_expr(Design*des, NetScope*scope,
				 ivl_type_t ntype, unsigned flags) const
{
      bool need_const = NEED_CONST & flags;

      symbol_search_results sr;
      symbol_search(this, des, scope, path_, lexical_pos_, &sr);

      if (!sr.net) {
            cerr << get_fileline() << ": error: Unable to bind variable `"
	         << path_ << "' in `" << scope_path(scope) << "'" << endl;
	    if (sr.decl_after_use) {
		  cerr << sr.decl_after_use->get_fileline() << ":      : "
			  "A symbol with that name was declared here. "
			  "Check for declaration after use." << endl;
	    }
	    des->errors++;
	    return nullptr;
      }

      NetNet *net = sr.net;

      if (!sr.path_tail.empty()) {
	    if (net->struct_type()) {
		  return check_for_struct_members(this, des, scope, net,
						  sr.path_head.back().index,
						  sr.path_tail);
	    } else if (dynamic_cast<const netclass_t*>(sr.type)) {
		  return elaborate_expr_class_field_(des, scope, sr, 0, flags);
	    }
      }

      if (debug_elaborate) {
	    cerr << get_fileline() << ": PEIdent::elaborate_expr: "
		 << "Found net " << net->name() << " for expr " << *this << endl;
      }

      ivl_type_t check_type = ntype;
      if (const netdarray_t*array_type = dynamic_cast<const netdarray_t*> (ntype)) {
            if (array_type->type_compatible(net->net_type())) {
                  NetESignal*tmp = new NetESignal(net);
                  tmp->set_line(*this);
                  return tmp;
            }

              // Icarus allows a dynamic array to be initialised with a
              // single elementary value, so try that next.
	    check_type = array_type->element_type();
      }

      if (! check_type->type_compatible(net->net_type())) {
	    cerr << get_fileline() << ": error: the type of the variable '"
		 << path_ << "' doesn't match the context type." << endl;

	    cerr << get_fileline() << ":      : " << "variable type=";
	    if (net->net_type())
		  net->net_type()->debug_dump(cerr);
	    else
		  cerr << "<nil>";
	    cerr << endl;

	    cerr << get_fileline() << ":      : " << "context type=";
	    ivl_assert(*this, ntype);
	    ntype->debug_dump(cerr);
	    cerr << endl;
	    des->errors += 1;
	    return 0;
      }
      ivl_assert(*this, ntype->type_compatible(net->net_type()));

      const name_component_t&use_comp = path_.back();

      if (debug_elaborate) {
	    cerr << get_fileline() << ": PEIdent::elaborate_expr: "
		 << "Typed ident " << net->name()
		 << " with " << use_comp.index.size() << " indices"
		 << " and " << net->unpacked_dimensions() << " expected."
		 << endl;
      }

// FIXME: The real array to queue is failing here.
      if (net->unpacked_dimensions() != use_comp.index.size()) {
	    cerr << get_fileline() << ": sorry: "
		 << "Net " << net->name()
		 << " expects " << net->unpacked_dimensions()
		 << ", but got " << use_comp.index.size() << "."
		 << endl;
	    des->errors += 1;

	    NetESignal*tmp = new NetESignal(net);
	    tmp->set_line(*this);
	    return tmp;
      }

      if (net->unpacked_dimensions() == 0) {
	    NetESignal*tmp = new NetESignal(net);
	    tmp->set_line(*this);
	    return tmp;
      }

	// Convert a set of index expressions to a single expression
	// that addresses the canonical element.
      list<NetExpr*>unpacked_indices;
      list<long> unpacked_indices_const;
      indices_flags idx_flags;
      indices_to_expressions(des, scope, this,
			     use_comp.index, net->unpacked_dimensions(),
			     need_const,
			     idx_flags,
			     unpacked_indices,
			     unpacked_indices_const);

      NetExpr*canon_index = 0;

      if (idx_flags.invalid) {
	      // Nothing to do

      } else if (idx_flags.undefined) {
	    cerr << get_fileline() << ": warning: "
		 << "returning 'bx for undefined array access "
		 << net->name() << as_indices(unpacked_indices)
		 << "." << endl;

      } else if (idx_flags.variable) {
	    ivl_assert(*this, unpacked_indices.size() == net->unpacked_dimensions());
	    canon_index = normalize_variable_unpacked(net, unpacked_indices);

      } else {
	    ivl_assert(*this, unpacked_indices_const.size() == net->unpacked_dimensions());
	    canon_index = normalize_variable_unpacked(net, unpacked_indices_const);
      }

      ivl_assert(*this, canon_index);
      NetESignal*tmp = new NetESignal(net, canon_index);
      tmp->set_line(*this);

      return tmp;
}

/*
 * Elaborate an identifier in an expression. The identifier can be a
 * parameter name, a signal name or a memory name. It can also be a
 * scope name (Return a NetEScope) but only certain callers can use
 * scope names. However, we still support it here.
 *
 * Function names are not handled here, they are detected by the
 * parser and are elaborated by PECallFunction.
 *
 * The signal name may be escaped, but that affects nothing here.
 */
NetExpr* PEIdent::elaborate_expr(Design*des, NetScope*scope,
				 unsigned expr_wid, unsigned flags) const
{
      NetExpr *result;

      result = elaborate_expr_(des, scope, expr_wid, flags);
      if (!result || !type_is_vectorable(expr_type_))
	    return result;

      auto net_type = result->net_type();
      if (net_type && !net_type->packed())
	    return result;

      return pad_to_width(result, expr_wid, signed_flag_, *this);
}

NetExpr* PEIdent::elaborate_expr_(Design*des, NetScope*scope,
				 unsigned expr_wid, unsigned flags) const
{
      ivl_assert(*this, scope);

      if (debug_elaborate) {
	    cerr << get_fileline() << ": PEIdent::elaborate_expr: "
		 << "path_=" << path_
		 << endl;
      }

      if (path_.size() > 1) {
            if (NEED_CONST & flags) {
                  cerr << get_fileline() << ": error: A hierarchical reference"
                          " (`" << path_ << "') is not allowed in a constant"
                          " expression." << endl;
                  des->errors += 1;
                  return 0;
            }
            if (scope->need_const_func()) {
                  cerr << get_fileline() << ": error: A hierarchical reference"
                          " (`" << path_ << "') is not allowed in a constant"
                          " function." << endl;
                  des->errors += 1;
                  return 0;
            }
            scope->is_const_func(false);
      }

	// Find the net/parameter/event object that this name refers
	// to. The path_ may be a scoped path, and may include method
	// or member name parts. For example, main.a.b.c may refer to
	// a net called "b" in the scope "main.a" and with a member
	// named "c". symbol_search() handles this for us.
      symbol_search_results sr;
      symbol_search(this, des, scope, path_, lexical_pos_, &sr);

	// If the identifier name is a parameter name, then return
	// the parameter value.
      if (sr.par_val != 0) {

	    if (!sr.path_tail.empty()) {
		  cerr << get_fileline() << ": error: Parameter name "
		       << sr.path_head << " can't have member names ("
		       << sr.path_tail << ")." << endl;
		  des->errors += 1;
	    }

	    return elaborate_expr_param_or_specparam_(des, scope, sr.par_val,
						      sr.scope, sr.type,
						      expr_wid, flags);
      }

	// If the identifier names a signal (a variable or a net)
	// then create a NetESignal node to handle it.
      if (sr.net != 0) {
            if (NEED_CONST & flags) {
                  cerr << get_fileline() << ": error: A reference to a net "
                          "or variable (`" << path_ << "') is not allowed in "
                          "a constant expression." << endl;
	          des->errors += 1;
                  return 0;
            }
            if (sr.net->scope()->type() == NetScope::MODULE) {
                  if (scope->need_const_func()) {
                        cerr << get_fileline() << ": error: A reference to a "
                                "non-local net or variable (`" << path_ << "') is "
                                "not allowed in a constant function." << endl;
                        des->errors += 1;
                        return 0;
                  }
                  scope->is_const_func(false);
            }

	      // If this is a struct, and there are members in the
	      // member_path, then generate an expression that
	      // reflects the member selection.
	    if (sr.net->struct_type() && !sr.path_tail.empty()) {
		  if (debug_elaborate) {
			cerr << get_fileline() << ": PEIdent::elaborate_expr: "
			        "Ident " << sr.path_head
			     << " look for struct member " << sr.path_tail
			     << endl;
		  }

		  return check_for_struct_members(this, des, scope, sr.net,
						  sr.path_head.back().index,
						  sr.path_tail);
	    }

	      // If this is an array object, and there are members in
	      // the sr.path_tail, check for array properties.
	    if (sr.net->darray_type() && !sr.path_tail.empty()) {
                  if (debug_elaborate) {
			cerr << get_fileline() << ": PEIdent::elaborate_expr: "
			        "Ident " << sr.path_head
			     << " looking for array property " << sr.path_tail
			     << endl;
                  }

		  ivl_assert(*this, sr.path_tail.size() == 1);
		  const name_component_t member_comp = sr.path_tail.front();
		  if (member_comp.name == "size") {
			NetESFunc*fun = new NetESFunc("$size",
						      &netvector_t::atom2s32,
						      1);
			fun->set_line(*this);

			NetESignal*arg = new NetESignal(sr.net);
			arg->set_line(*sr.net);

			fun->parm(0, arg);
			return fun;
		  } else if (member_comp.name == "find") {
			cerr << get_fileline() << ": sorry: 'find()' "
			        "array location method is not currently "
			        "implemented." << endl;
			des->errors += 1;
			return 0;
		  } else if (member_comp.name == "find_index") {
			cerr << get_fileline() << ": sorry: 'find_index()' "
			        "array location method is not currently "
			        "implemented." << endl;
			des->errors += 1;
			return 0;
		  } else if (member_comp.name == "find_first") {
			cerr << get_fileline() << ": sorry: 'find_first()' "
			        "array location method is not currently "
			        "implemented." << endl;
			des->errors += 1;
			return 0;
		  } else if (member_comp.name == "find_first_index") {
			cerr << get_fileline() << ": sorry: 'find_first_index()' "
			        "array location method is not currently "
			        "implemented." << endl;
			des->errors += 1;
			return 0;
		  } else if (member_comp.name == "find_last") {
			cerr << get_fileline() << ": sorry: 'find_last()' "
			        "array location method is not currently "
			        "implemented." << endl;
			des->errors += 1;
			return 0;
		  } else if (member_comp.name == "find_last_index") {
			cerr << get_fileline() << ": sorry: 'find_last_index()' "
			        "array location method is not currently "
			        "implemented." << endl;
			des->errors += 1;
			return 0;
		  } else if (member_comp.name == "min") {
			cerr << get_fileline() << ": sorry: 'min()' "
			        "array location method is not currently "
			        "implemented." << endl;
			des->errors += 1;
			return 0;
		  } else if (member_comp.name == "max") {
			cerr << get_fileline() << ": sorry: 'max()' "
			        "array location method is not currently "
			        "implemented." << endl;
			des->errors += 1;
			return 0;
		  } else if (member_comp.name == "unique") {
			cerr << get_fileline() << ": sorry: 'unique()' "
			        "array location method is not currently "
			        "implemented." << endl;
			des->errors += 1;
			return 0;
		  } else if (member_comp.name == "unique_index") {
			cerr << get_fileline() << ": sorry: 'unique_index()' "
			        "array location method is not currently "
			        "implemented." << endl;
			des->errors += 1;
			return 0;
// FIXME: Check this is a real or integral type.
		  } else if (member_comp.name == "sum") {
			cerr << get_fileline() << ": sorry: 'sum()' "
			        "array reduction method is not currently "
			        "implemented." << endl;
			des->errors += 1;
			return 0;
		  } else if (member_comp.name == "product") {
			cerr << get_fileline() << ": sorry: 'product()' "
			        "array reduction method is not currently "
			        "implemented." << endl;
			des->errors += 1;
			return 0;
// FIXME: Check this is only an integral type.
		  } else if (member_comp.name == "and") {
			cerr << get_fileline() << ": sorry: 'and()' "
			        "array reduction method is not currently "
			        "implemented." << endl;
			des->errors += 1;
			return 0;
		  } else if (member_comp.name == "or") {
			cerr << get_fileline() << ": sorry: 'or()' "
			        "array reduction method is not currently "
			        "implemented." << endl;
			des->errors += 1;
			return 0;
		  } else if (member_comp.name == "xor") {
			cerr << get_fileline() << ": sorry: 'xor()' "
			        "array reduction method is not currently "
			        "implemented." << endl;
			des->errors += 1;
			return 0;
		  }
	    }

	      // If this is a queue object, and there are members in
	      // the sr.path_tail, check for array properties.
	    if (sr.net->queue_type() && !sr.path_tail.empty()) {
                  if (debug_elaborate) {
                        cerr << get_fileline() << ": PEIdent::elaborate_expr: "
                             << "Ident " << sr.path_head
                             << " looking for queue property " << sr.path_tail
                             << endl;
                  }

		  ivl_assert(*this, sr.path_tail.size() == 1);
		  const name_component_t member_comp = sr.path_tail.front();
		  const netqueue_t*queue = sr.net->queue_type();
		  ivl_type_t element_type = queue->element_type();
		  if (member_comp.name == "pop_back") {
			NetESFunc*fun = new NetESFunc("$ivl_queue_method$pop_back",
			                              element_type, 1);
			fun->set_line(*this);

			NetESignal*arg = new NetESignal(sr.net);
			arg->set_line(*sr.net);

			fun->parm(0, arg);
			return fun;
		  }

		  if (member_comp.name == "pop_front") {
			NetESFunc*fun = new NetESFunc("$ivl_queue_method$pop_front",
			                              element_type, 1);
			fun->set_line(*this);

			NetESignal*arg = new NetESignal(sr.net);
			arg->set_line(*sr.net);

			fun->parm(0, arg);
			return fun;
		  }
	    }

	    if ((sr.net->data_type() == IVL_VT_STRING) && !sr.path_tail.empty()) {
		  if (debug_elaborate) {
			cerr << get_fileline() << ": PEIdent::elaborate_expr: "
			        "Ident " << sr.path_head
			     << " looking for string property " << sr.path_tail
			     << endl;
		  }

		  ivl_assert(*this, sr.path_tail.size() == 1);
		  const name_component_t member_comp = sr.path_tail.front();
		  cerr << get_fileline() << ": sorry: String method '"
		       << member_comp.name << "' currently requires ()."
		       << endl;
		  des->errors += 1;
		  return 0;
	    }

	    if (dynamic_cast<const netclass_t*>(sr.type) && !sr.path_tail.empty()) {
		  return elaborate_expr_class_field_(des, scope, sr,
						     expr_wid, flags);
	    }

	    if (sr.net->enumeration() && !sr.path_tail.empty()) {
		  const netenum_t*netenum = sr.net->enumeration();
		  if (debug_elaborate) {
			cerr << get_fileline() << ": PEIdent::elaborate_expr: "
			        "Ident " << sr.path_head
			     << " look for enumeration method " << sr.path_tail
			     << endl;
		  }

		  NetESignal*expr = new NetESignal(sr.net);
		  expr->set_line(*this);
		  ivl_assert(*this, sr.path_tail.size() == 1);
		  const name_component_t member_comp = sr.path_tail.front();
		  ivl_assert(*this, member_comp.index.empty());
		  return check_for_enum_methods(this, des, scope,
						netenum, sr.path_head,
						member_comp.name,
						expr, {});
	    }

	    ivl_assert(*this, sr.path_tail.empty());
	    NetExpr*tmp = elaborate_expr_net(des, scope, sr.net, sr.scope,
                                             expr_wid, flags);

            if (!tmp) return 0;

	    if (debug_elaborate) {
		  cerr << get_fileline() << ": PEIdent::elaborate_expr: "
		          "Expression as net. expr_wid=" << expr_wid
		       << ", tmp->expr_width()=" << tmp->expr_width()
		       << ", tmp=" << *tmp << endl;
	    }

            return tmp;
      }

	// If the identifier is a named event
        // then create a NetEEvent node to handle it.
      if (sr.eve != 0) {
            if (NEED_CONST & flags) {
                  cerr << get_fileline() << ": error: A reference to a named "
                          "event (`" << path_ << "') is not allowed in a "
                          "constant expression." << endl;
	          des->errors += 1;
                  return 0;
            }
            if (sr.eve->scope() != scope) {
                  if (scope->need_const_func()) {
                        cerr << get_fileline() << ": error: A reference to a "
                                "non-local named event (`" << path_ << "') is "
                                "not allowed in a constant function." << endl;
                        des->errors += 1;
                        return 0;
                  }
                  scope->is_const_func(false);
            }

	    if (!sr.path_tail.empty()) {
		  cerr << get_fileline() << ": error: Event name "
		       << sr.path_head << " can't have member names ("
		       << sr.path_tail << ")" << endl;
		  des->errors += 1;
	    }

	    NetEEvent*tmp = new NetEEvent(sr.eve);
	    tmp->set_line(*this);
	    return tmp;
      }

	// Hmm... maybe this is a genvar? This is only possible while
	// processing generate blocks, but then the genvar_tmp will be
	// set in the scope.
      if (path_.size() == 1
	  && scope->genvar_tmp.str()
	  && strcmp(peek_tail_name(path_), scope->genvar_tmp) == 0) {
	    if (debug_elaborate)
		  cerr << get_fileline() << ": debug: " << path_
		       << " is genvar with value " << scope->genvar_tmp_val
		       << "." << endl;
	    verinum val (scope->genvar_tmp_val, expr_wid);
	    val.has_sign(true);
	    NetEConst*tmp = new NetEConst(val);
	    tmp->set_line(*this);
	    return tmp;
      }


	// At this point we've exhausted all the possibilities that
	// are not scopes. If this is not a system task argument, then
	// it cannot be a scope name, so give up.

      if ( !(SYS_TASK_ARG & flags) ) {
	      // I cannot interpret this identifier. Error message.
            cerr << get_fileline() << ": error: Unable to bind "
                 << ((NEED_CONST & flags) ? "parameter" : "wire/reg/memory")
                 << " `" << path_ << "' in `" << scope_path(scope) << "'"
                 << endl;
            if (scope->need_const_func()) {
                  cerr << get_fileline() << ":      : `" << scope->basename()
                       << "' is being used as a constant function, so may "
                          "only reference local variables." << endl;
            }
	    if (sr.decl_after_use) {
		  cerr << sr.decl_after_use->get_fileline() << ":      : "
			  "A symbol with that name was declared here. "
			  "Check for declaration after use." << endl;
	    }
	    des->errors += 1;
	    return 0;
      }

	// Finally, if this is a scope name, then return that. Look
	// first to see if this is a name of a local scope. Failing
	// that, search globally for a hierarchical name.
      if ((path_.size() == 1)) {
	    hname_t use_name ( peek_tail_name(path_) );
	    if (NetScope*nsc = scope->child(use_name)) {
		  NetEScope*tmp = new NetEScope(nsc);
		  tmp->set_line(*this);

		  if (debug_elaborate)
			cerr << get_fileline() << ": debug: Found scope "
			     << use_name << " in scope " << scope->basename()
			     << endl;

		  return tmp;
	    }
      }

      list<hname_t> spath = eval_scope_path(des, scope, path_.name);

      ivl_assert(*this, spath.size() == path_.size());

	// Try full hierarchical scope name.
      if (NetScope*nsc = des->find_scope(spath)) {
	    NetEScope*tmp = new NetEScope(nsc);
	    tmp->set_line(*this);

	    if (debug_elaborate)
		  cerr << get_fileline() << ": debug: Found scope "
		       << nsc->basename()
		       << " path=" << path_ << endl;

	    if ( !(SYS_TASK_ARG & flags) ) {
		  cerr << get_fileline() << ": error: Scope name "
		       << nsc->basename() << " not allowed here." << endl;
		  des->errors += 1;
	    }

	    return tmp;
      }

	// Try relative scope name.
      if (NetScope*nsc = des->find_scope(scope, spath)) {
	    NetEScope*tmp = new NetEScope(nsc);
	    tmp->set_line(*this);

	    if (debug_elaborate)
		  cerr << get_fileline() << ": debug: Found scope "
		       << nsc->basename() << " in " << scope_path(scope) << endl;

	    return tmp;
      }

	// I cannot interpret this identifier. Error message.
      cerr << get_fileline() << ": error: Unable to bind wire/reg/memory "
              "`" << path_ << "' in `" << scope_path(scope) << "'" << endl;
      des->errors += 1;
      return 0;
}

static verinum param_part_select_bits(const verinum&par_val, long wid,
				     long lsv)
{
      verinum result (verinum::Vx, wid, true);

      for (long idx = 0 ; idx < wid ; idx += 1) {
	    long off = idx + lsv;
	    if (off < 0)
		  continue;
	    else if (off < (long)par_val.len())
		  result.set(idx, par_val.get(off));
	    else if (par_val.is_string()) // Pad strings with nulls.
		  result.set(idx, verinum::V0);
	    else if (par_val.has_len()) // Pad sized parameters with X
		  continue;
	    else // Unsized parameters are "infinite" width.
		  result.set(idx, sign_bit(par_val));
      }

	// If the input is a string, and the part select is working on
	// byte boundaries, then make the result into a string.
      if (par_val.is_string() && (labs(lsv)%8 == 0) && (wid%8 == 0))
	    return verinum(result.as_string());

      return result;
}

NetExpr* PEIdent::elaborate_expr_param_bit_(Design*des, NetScope*scope,
					    const NetExpr*par,
					    const NetScope*found_in,
					    ivl_type_t par_type,
                                            bool need_const) const
{
      const NetEConst*par_ex = dynamic_cast<const NetEConst*> (par);
      ivl_assert(*this, par_ex);

      long par_msv, par_lsv;
      if(! calculate_param_range(*this, par_type, par_msv, par_lsv,
				 par_ex->value().len())) return 0;

      const name_component_t&name_tail = path_.back();
      ivl_assert(*this, !name_tail.index.empty());
      const index_component_t&index_tail = name_tail.index.back();
      ivl_assert(*this, index_tail.msb);
      ivl_assert(*this, !index_tail.lsb);

      NetExpr*sel = elab_and_eval(des, scope, index_tail.msb, -1, need_const);
      if (sel == 0) return 0;

      perm_string name = peek_tail_name(path_);

      if (sel->expr_type() == IVL_VT_REAL) {
	    cerr << get_fileline() << ": error: Index expression for "
	         << name << "[" << *sel
	         << "] cannot be a real value." << endl;
	    des->errors += 1;
	    return 0;
      }

      if (debug_elaborate)
	    cerr << get_fileline() << ": debug: Calculate bit select "
		 << name << "[" << *sel << "] from range "
		 << "[" << par_msv << ":" << par_lsv << "]." << endl;

	// Handle the special case that the selection is constant. In this
	// case, just precalculate the entire constant result.
      if (NetEConst*sel_c = dynamic_cast<NetEConst*> (sel)) {
	      // Special case: If the bit select is constant and not fully
	      // defined, then we know that the result must be 1'bx.
	    if (! sel_c->value().is_defined()) {
		  if (warn_ob_select) {
			cerr << get_fileline() << ": warning: "
			        "Constant undefined bit select ["
			     << sel_c->value() << "] for parameter '"
			     << name << "'." << endl;
			cerr << get_fileline() << ":        : "
			        "Replacing select with a constant 1'bx."
			     << endl;
		  }
		  NetEConst*res = make_const_x(1);
		  res->set_line(*this);
		  return res;
	    }
	      // Calculate the canonical index value.
	    long sel_v = sel_c->value().as_long();
	    if (par_msv >= par_lsv) sel_v -= par_lsv;
	    else sel_v = par_lsv - sel_v;

	      // Select a bit from the parameter.
	    verinum par_v = par_ex->value();
	    verinum::V rtn = verinum::Vx;

	      // A constant in range select.
	    if ((sel_v >= 0) && ((unsigned long) sel_v < par_v.len())) {
		  rtn = par_v[sel_v];
	      // An unsized after select.
	    } else if ((sel_v >= 0) && (! par_v.has_len())) {
		  if (par_v.has_sign()) rtn = par_v[par_v.len()-1];
		  else rtn = verinum::V0;
	    } else if (warn_ob_select) {
		  cerr << get_fileline() << ": warning: "
		          "Constant bit select [" << sel_c->value().as_long()
		       << "] is ";
		  if (sel_v < 0) cerr << "before ";
		  else cerr << "after ";
		  cerr << name << "[";
		  if (par_v.has_len()) cerr << par_msv;
		  else cerr << "<inf>";
		  cerr << ":" << par_lsv << "]." << endl;
		  cerr << get_fileline() << ":        : "
		          "Replacing select with a constant 1'bx." << endl;
	    }
	    NetEConst*res = new NetEConst(verinum(rtn, 1));
	    res->set_line(*this);
	    return res;
      }

      sel = normalize_variable_base(sel, par_msv, par_lsv, 1, true);

	/* Create a parameter reference for the variable select. */
      NetEConstParam*ptmp = new NetEConstParam(found_in, name, par_ex->value());
      ptmp->set_line(found_in->get_parameter_line_info(name));

      NetExpr*tmp = new NetESelect(ptmp, sel, 1);
      tmp->set_line(*this);
      return tmp;
}

NetExpr* PEIdent::elaborate_expr_param_part_(Design*des, NetScope*scope,
					     const NetExpr*par,
					     const NetScope*,
					     ivl_type_t par_type,
                                             unsigned expr_wid) const
{
      long msv, lsv;
      bool parts_defined_flag;
      bool flag = calculate_parts_(des, scope, msv, lsv, parts_defined_flag);
      if (!flag)
	    return 0;

      const NetEConst*par_ex = dynamic_cast<const NetEConst*> (par);
      ivl_assert(*this, par_ex);


      long par_msv, par_lsv;
      if (! calculate_param_range(*this, par_type, par_msv, par_lsv,
				  par_ex->value().len())) return 0;

      if (! parts_defined_flag) {
	    if (warn_ob_select) {
		  const index_component_t&psel = path_.back().index.back();
		  perm_string name = peek_tail_name(path_);
		  cerr << get_fileline() << ": warning: "
		          "Undefined part select [" << *(psel.msb) << ":"
		       << *(psel.lsb) << "] for parameter '" << name
		       << "'." << endl;
		  cerr << get_fileline() << ":        : "
		          "Replacing select with a constant 'bx." << endl;
	    }

	    verinum val(verinum::Vx, expr_wid, true);
	    NetEConst*tmp = new NetEConst(val);
	    tmp->set_line(*this);
	    return tmp;
      }

	// Notice that the par_msv is not used in this function other
	// than for this test. It is used to tell the direction that
	// the bits are numbers, so that we can make sure the
	// direction matches the part select direction. After that,
	// we only need the par_lsv.
      if ((msv>lsv && par_msv<par_lsv) || (msv<lsv && par_msv>=par_lsv)) {
	    perm_string name = peek_tail_name(path_);
	    cerr << get_fileline() << ": error: Part select " << name
		 << "[" << msv << ":" << lsv << "] is out of order." << endl;
	    des->errors += 1;
	    return 0;
      }

      long wid = 1 + labs(msv-lsv);

	// Watch out for reversed bit numbering. We're making
	// the part select from LSB to MSB.
      long base;
      if (par_msv < par_lsv) {
	    base = par_lsv - lsv;
      } else {
	    base = lsv - par_lsv;
      }

      if (warn_ob_select) {
	    if (base < 0) {
		  perm_string name = peek_tail_name(path_);
		  cerr << get_fileline() << ": warning: Part select "
		       << "[" << msv << ":" << lsv << "] is selecting "
		          "before the parameter " << name << "[";
		  if (par_ex->value().has_len()) cerr << par_msv;
		  else cerr << "<inf>";
		  cerr << ":" << par_lsv << "]." << endl;
		  cerr << get_fileline() << ":        : Replacing "
		          "the out of bound bits with 'bx." << endl;
	    }
	    if (par_ex->value().has_len() &&
                (base+wid > (long)par->expr_width())) {
		  perm_string name = peek_tail_name(path_);
		  cerr << get_fileline() << ": warning: Part select "
		       << name << "[" << msv << ":" << lsv << "] is selecting "
		          "after the parameter " << name << "[" << par_msv
		       << ":" << par_lsv << "]." << endl;
		  cerr << get_fileline() << ":        : Replacing "
		          "the out of bound bits with 'bx." << endl;
	    }
      }

      verinum result = param_part_select_bits(par_ex->value(), wid, base);
      NetEConst*result_ex = new NetEConst(result);
      result_ex->set_line(*this);

      return result_ex;
}

static void warn_param_ob(long par_msv, long par_lsv, bool defined,
                          long par_base, unsigned long wid, long pwid,
                          const LineInfo *info, perm_string name, bool up)
{
      long par_max;

      if (defined) {
	    if (par_msv < par_lsv) par_max = par_lsv-par_msv;
	     else par_max = par_msv-par_lsv;
      } else {
	    if (pwid < 0) par_max = integer_width;
	    else par_max = pwid;
      }

	/* Is this a select before the start of the parameter? */
      if (par_base < 0) {
	    cerr << info->get_fileline() << ": warning: " << name << "["
	         << par_base;
	    if (up) cerr << "+:";
	    else cerr << "-:";
	    cerr << wid << "] is selecting before vector." << endl;
      }

	/* Is this a select after the end of the parameter? */
      if (par_base + (long)wid - 1 > par_max) {
	    cerr << info->get_fileline() << ": warning: " << name << "["
	         << par_base;
	    if (up) cerr << "+:";
	    else cerr << "-:";
	    cerr << wid << "] is selecting after vector." << endl;
      }
}

NetExpr* PEIdent::elaborate_expr_param_idx_up_(Design*des, NetScope*scope,
					       const NetExpr*par,
					       const NetScope*found_in,
					       ivl_type_t par_type,
                                               bool need_const) const
{
      const NetEConst*par_ex = dynamic_cast<const NetEConst*> (par);
      ivl_assert(*this, par_ex);

      long par_msv, par_lsv;
      if(! calculate_param_range(*this, par_type, par_msv, par_lsv,
				 par_ex->value().len())) return 0;

      NetExpr*base = calculate_up_do_base_(des, scope, need_const);
      if (base == 0) return 0;

	// Use the part select width already calculated by test_width().
      unsigned long wid = min_width_;

      perm_string name = peek_tail_name(path_);

      if (debug_elaborate)
	    cerr << get_fileline() << ": debug: Calculate part select "
		 << name << "[" << *base << "+:" << wid << "] from range "
		 << "[" << par_msv << ":" << par_lsv << "]." << endl;

      if (base->expr_type() == IVL_VT_REAL) {
	    cerr << get_fileline() << ": error: Indexed part select base "
	            "expression for " << name << "[" << *base << "+:" << wid
	         << "] cannot be a real value." << endl;
	    des->errors += 1;
	    return 0;
      }

	// Handle the special case that the base is constant. In this
	// case, just precalculate the entire constant result.
      if (NetEConst*base_c = dynamic_cast<NetEConst*> (base)) {
	    if (! base_c->value().is_defined()) {
		  NetEConst *ex;
		  ex = new NetEConst(verinum(verinum::Vx, wid, true));
		  ex->set_line(*this);
		  if (warn_ob_select) {
			cerr << get_fileline() << ": warning: " << name
			     << "['bx+:" << wid
			     << "] is always outside vector." << endl;
		  }
		  return ex;
	    }
	    long lsv = base_c->value().as_long();
	    long par_base = par_lsv;

	      // Watch out for reversed bit numbering. We're making
	      // the part select from LSB to MSB.
	    if (par_msv < par_lsv) {
		  par_base = lsv;
		  lsv = par_lsv - wid + 1;
	    }

	    if (warn_ob_select) {
                  bool defined = true;
		    // Check to see if the parameter has a defined range.
                  if (par_type == 0) {
			defined = false;
                  }
		    // Get the parameter values width.
                  long pwid = -1;
                  if (par_ex->has_width()) pwid = par_ex->expr_width()-1;
                  warn_param_ob(par_msv, par_lsv, defined, lsv-par_base, wid,
                                pwid, this, name, true);
	    }
	    verinum result = param_part_select_bits(par_ex->value(), wid,
						    lsv-par_base);
	    NetEConst*result_ex = new NetEConst(result);
	    result_ex->set_line(*this);
	    return result_ex;
      }

      base = normalize_variable_base(base, par_msv, par_lsv, wid, true);

	/* Create a parameter reference for the variable select. */
      NetEConstParam*ptmp = new NetEConstParam(found_in, name, par_ex->value());
      ptmp->set_line(found_in->get_parameter_line_info(name));

      NetExpr*tmp = new NetESelect(ptmp, base, wid, IVL_SEL_IDX_UP);
      tmp->set_line(*this);
      return tmp;
}

NetExpr* PEIdent::elaborate_expr_param_idx_do_(Design*des, NetScope*scope,
					       const NetExpr*par,
					       const NetScope*found_in,
					       ivl_type_t par_type,
                                               bool need_const) const
{
      const NetEConst*par_ex = dynamic_cast<const NetEConst*> (par);
      ivl_assert(*this, par_ex);

      long par_msv, par_lsv;
      if(! calculate_param_range(*this, par_type, par_msv, par_lsv,
				 par_ex->value().len())) return 0;

      NetExpr*base = calculate_up_do_base_(des, scope, need_const);
      if (base == 0) return 0;

	// Use the part select width already calculated by test_width().
      unsigned long wid = min_width_;

      perm_string name = peek_tail_name(path_);

      if (debug_elaborate)
	    cerr << get_fileline() << ": debug: Calculate part select "
		 << name << "[" << *base << "-:" << wid << "] from range "
		 << "[" << par_msv << ":" << par_lsv << "]." << endl;

      if (base->expr_type() == IVL_VT_REAL) {
	    cerr << get_fileline() << ": error: Indexed part select base "
	            "expression for " << name << "[" << *base << "-:" << wid
	         << "] cannot be a real value." << endl;
	    des->errors += 1;
	    return 0;
      }

	// Handle the special case that the base is constant. In this
	// case, just precalculate the entire constant result.
      if (NetEConst*base_c = dynamic_cast<NetEConst*> (base)) {
	    if (! base_c->value().is_defined()) {
		  NetEConst *ex;
		  ex = new NetEConst(verinum(verinum::Vx, wid, true));
		  ex->set_line(*this);
		  if (warn_ob_select) {
			cerr << get_fileline() << ": warning: " << name
			     << "['bx-:" << wid
			     << "] is always outside vector." << endl;
		  }
		  return ex;
	    }
	    long lsv = base_c->value().as_long();
	    long par_base = par_lsv + wid - 1;

	      // Watch out for reversed bit numbering. We're making
	      // the part select from LSB to MSB.
	    if (par_msv < par_lsv) {
		  par_base = lsv;
		  lsv = par_lsv;
	    }

	    if (warn_ob_select) {
                  bool defined = true;
		    // Check to see if the parameter has a defined range.
                  if (par_type == 0) {
			defined = false;
                  }
		    // Get the parameter values width.
                  long pwid = -1;
                  if (par_ex->has_width()) pwid = par_ex->expr_width()-1;
                  warn_param_ob(par_msv, par_lsv, defined, lsv-par_base, wid,
                                pwid, this, name, false);
	    }

	    verinum result = param_part_select_bits(par_ex->value(), wid,
						    lsv-par_base);
	    NetEConst*result_ex = new NetEConst(result);
	    result_ex->set_line(*this);
	    return result_ex;
      }

      base = normalize_variable_base(base, par_msv, par_lsv, wid, false);

	/* Create a parameter reference for the variable select. */
      NetEConstParam*ptmp = new NetEConstParam(found_in, name, par_ex->value());
      ptmp->set_line(found_in->get_parameter_line_info(name));

      NetExpr*tmp = new NetESelect(ptmp, base, wid, IVL_SEL_IDX_DOWN);
      tmp->set_line(*this);
      return tmp;
}

NetExpr* PEIdent::elaborate_expr_param_or_specparam_(Design*des,
						     NetScope*scope,
						     const NetExpr*par,
						     NetScope*found_in,
						     ivl_type_t par_type,
						     unsigned expr_wid,
						     unsigned flags) const
{
      bool need_const = NEED_CONST & flags;

      if (need_const && !(ANNOTATABLE & flags)) {
            perm_string name = peek_tail_name(path_);
            if (found_in->make_parameter_unannotatable(name)) {
                  cerr << get_fileline() << ": warning: specparam '" << name
                       << "' is being used in a constant expression." << endl;
                  cerr << get_fileline() << ":        : This will prevent it "
                          "being annotated at run time." << endl;
            }
      }

      return elaborate_expr_param_(des, scope, par, found_in, par_type,
			           expr_wid, flags);
}


/*
 * Handle the case that the identifier is a parameter reference. The
 * parameter expression has already been located for us (as the par
 * argument) so we just need to process the sub-expression.
 */
NetExpr* PEIdent::elaborate_expr_param_(Design*des,
					NetScope*scope,
					const NetExpr*par,
					const NetScope*found_in,
					ivl_type_t par_type,
					unsigned expr_wid, unsigned flags) const
{
      bool need_const = NEED_CONST & flags;

      if (debug_elaborate) {
	    cerr << get_fileline() << ": " << __func__ << ": "
		 << "Parameter: " << path_ << endl;
	    if (par_type)
		  cerr << get_fileline() << ": " << __func__ << ": "
		       << "par_type: " << *par_type << endl;
	    else
		  cerr << get_fileline() << ": " << __func__ << ": "
		       << "par_type: <nil>" << endl;
      }

      const name_component_t&name_tail = path_.back();
      index_component_t::ctype_t use_sel = index_component_t::SEL_NONE;
      if (!name_tail.index.empty())
	    use_sel = name_tail.index.back().sel;

      if (par->expr_type() == IVL_VT_REAL &&
          use_sel != index_component_t::SEL_NONE) {
	    perm_string name = peek_tail_name(path_);
	    cerr << get_fileline() << ": error: "
	         << "can not select part of real parameter: " << name << endl;
	    des->errors += 1;
	    return 0;
      }

      ivl_assert(*this, use_sel != index_component_t::SEL_BIT_LAST);

      if (use_sel == index_component_t::SEL_BIT)
	    return elaborate_expr_param_bit_(des, scope, par, found_in,
					     par_type, need_const);

      if (use_sel == index_component_t::SEL_PART)
	    return elaborate_expr_param_part_(des, scope, par, found_in,
					      par_type, expr_wid);

      if (use_sel == index_component_t::SEL_IDX_UP)
	    return elaborate_expr_param_idx_up_(des, scope, par, found_in,
						par_type, need_const);

      if (use_sel == index_component_t::SEL_IDX_DO)
	    return elaborate_expr_param_idx_do_(des, scope, par, found_in,
						par_type, need_const);

      NetExpr*tmp = 0;

      const NetEConstEnum*etmp = dynamic_cast<const NetEConstEnum*>(par);
      if (etmp) {
	    if (debug_elaborate)
		  cerr << get_fileline() << ": debug: "
		       << "Elaborate parameter <" << path_
		       << "> as enumeration constant." << *etmp << endl;
	    tmp = etmp->dup_expr();
      } else {
	    perm_string name = peek_tail_name(path_);

	      /* No bit or part select. Make the constant into a
		 NetEConstParam or NetECRealParam as appropriate. */
	    const NetEConst*ctmp = dynamic_cast<const NetEConst*>(par);
	    if (ctmp) {
                  verinum cvalue = ctmp->value();
                  if (cvalue.has_len())
			cvalue.has_sign(signed_flag_);
                  cvalue = cast_to_width(cvalue, expr_wid);
		  tmp = new NetEConstParam(found_in, name, cvalue);
		  tmp->cast_signed(signed_flag_);
		  tmp->set_line(*par);

		  if (debug_elaborate)
			cerr << get_fileline() << ": debug: "
			     << "Elaborate parameter <" << name
			     << "> as constant " << *tmp << endl;
	    }

	    const NetECReal*rtmp = dynamic_cast<const NetECReal*>(par);
	    if (rtmp) {
		  tmp = new NetECRealParam(found_in, name, rtmp->value());
		  tmp->set_line(*par);

		  if (debug_elaborate)
			cerr << get_fileline() << ": debug: "
			     << "Elaborate parameter <" << name
			     << "> as constant " << *tmp << endl;
	    }
	      /* The numeric parameter value needs to have the file and line
	       * information for the actual parameter not the expression. */
	    ivl_assert(*this, tmp);
	    tmp->set_line(found_in->get_parameter_line_info(name));
      }

      return tmp;
}

/*
 * Handle word selects of vector arrays.
 */
NetExpr* PEIdent::elaborate_expr_net_word_(Design*des, NetScope*scope,
					   NetNet*net, NetScope*found_in,
                                           unsigned expr_wid,
					   unsigned flags) const
{
      bool need_const = NEED_CONST & flags;

      const name_component_t&name_tail = path_.back();

      if (debug_elaborate) {
	    cerr << get_fileline() << ": PEIdent::elaborate_net_word_: "
		 << "expr_wid=" << expr_wid
		 << ", net->get_scalar()==" << (net->get_scalar()?"true":"false")
		 << endl;
      }

	// Special case: This is the entire array, and we are a direct
	// argument of a system task.
      if (name_tail.index.empty() && (SYS_TASK_ARG & flags)) {
	    NetESignal*res = new NetESignal(net, 0);
	    res->set_line(*this);
	    return res;
      }

      if (name_tail.index.empty()) {
	    cerr << get_fileline() << ": error: Array " << path()
		 << " needs an array index here." << endl;
	    des->errors += 1;
	    return 0;
      }

	// Make sure there are enough indices to address an array element.
      if (name_tail.index.size() < net->unpacked_dimensions()) {
	    cerr << get_fileline() << ": error: Array " << path()
		 << " needs " << net->unpacked_dimensions() << " indices,"
		 << " but got only " << name_tail.index.size() << "." << endl;
	    des->errors += 1;
	    return 0;
      }

	// Evaluate all the index expressions into an
	// "unpacked_indices" array.
      list<NetExpr*>unpacked_indices;
      list<long> unpacked_indices_const;
      indices_flags idx_flags;
      indices_to_expressions(des, scope, this,
			     name_tail.index, net->unpacked_dimensions(),
			     need_const,
			     idx_flags,
			     unpacked_indices,
			     unpacked_indices_const);

      NetExpr*canon_index = 0;
      if (idx_flags.invalid) {
	    // Nothing to do.

      } else if (idx_flags.undefined) {
	    cerr << get_fileline() << ": warning: "
		 << "returning 'bx for undefined array access "
		 << net->name() << as_indices(unpacked_indices)
		 << "." << endl;

      } else if (idx_flags.variable) {
	    ivl_assert(*this, unpacked_indices.size() == net->unpacked_dimensions());
	    canon_index = normalize_variable_unpacked(net, unpacked_indices);

      } else {
	    ivl_assert(*this, unpacked_indices_const.size() == net->unpacked_dimensions());
	    canon_index = normalize_variable_unpacked(net, unpacked_indices_const);

	    if (canon_index == 0) {
		  cerr << get_fileline() << ": warning: "
		       << "returning 'bx for out of bounds array access "
		       << net->name() << as_indices(unpacked_indices_const)
		       << "." << endl;
	    }
      }

      if (canon_index == 0) {
	    NetEConst*xxx = make_const_x(net->vector_width());
	    xxx->set_line(*this);
	    return xxx;
      }
      canon_index->set_line(*this);

      NetESignal*res = new NetESignal(net, canon_index);
      res->set_line(*this);

	// Detect that the word has a bit/part select as well.

      index_component_t::ctype_t word_sel = index_component_t::SEL_NONE;
      if (name_tail.index.size() > net->unpacked_dimensions())
	    word_sel = name_tail.index.back().sel;

      if (net->get_scalar() &&
          word_sel != index_component_t::SEL_NONE) {
	    cerr << get_fileline() << ": error: can not select part of ";
	    if (res->expr_type() == IVL_VT_REAL) cerr << "real";
	    else cerr << "scalar";
	    cerr << " array word: " << net->name()
		 << as_indices(unpacked_indices) << endl;
	    des->errors += 1;
	    delete res;
	    return 0;
      }

      if (word_sel == index_component_t::SEL_PART)
	    return elaborate_expr_net_part_(des, scope, res, found_in,
                                            expr_wid);

      if (word_sel == index_component_t::SEL_IDX_UP)
	    return elaborate_expr_net_idx_up_(des, scope, res, found_in,
                                              need_const);

      if (word_sel == index_component_t::SEL_IDX_DO)
	    return elaborate_expr_net_idx_do_(des, scope, res, found_in,
                                              need_const);

      if (word_sel == index_component_t::SEL_BIT)
	    return elaborate_expr_net_bit_(des, scope, res, found_in,
                                           need_const);

      ivl_assert(*this, word_sel == index_component_t::SEL_NONE);

      return res;
}

/*
 * Handle part selects of NetNet identifiers.
 */
NetExpr* PEIdent::elaborate_expr_net_part_(Design*des, NetScope*scope,
				           NetESignal*net, NetScope*,
                                           unsigned expr_wid) const
{
      if (net->sig()->data_type() == IVL_VT_STRING) {
	    cerr << get_fileline() << ": error: Cannot take the part select of a string ('"
	         << net->name() << "')." << endl;
	    des->errors += 1;
	    return 0;
      }

      list<long> prefix_indices;
      bool rc = calculate_packed_indices_(des, scope, net->sig(), prefix_indices);
      if (!rc)
	    return 0;

      long msv, lsv;
      bool parts_defined_flag;
      bool flag = calculate_parts_(des, scope, msv, lsv, parts_defined_flag);
      if (!flag)
	    return 0;

	/* But wait... if the part select expressions are not fully
	   defined, then fall back on the tested width. */
      if (!parts_defined_flag) {
	    if (warn_ob_select) {
		  const index_component_t&psel = path_.back().index.back();
		  cerr << get_fileline() << ": warning: "
		          "Undefined part select [" << *(psel.msb) << ":"
		       << *(psel.lsb) << "] for ";
		  if (net->word_index()) cerr << "array word";
		  else cerr << "vector";
		  cerr << " '" << net->name();
		  if (net->word_index()) cerr << "[]";
		  cerr << "'." << endl;
		  cerr << get_fileline() << ":        : "
		          "Replacing select with a constant 'bx." << endl;
	    }

	    NetEConst*tmp = new NetEConst(verinum(verinum::Vx, expr_wid, true));
	    tmp->set_line(*this);
	    return tmp;
      }
      long sb_lsb, sb_msb;
      if (prefix_indices.size()+1 < net->sig()->packed_dims().size()) {
	      // Here we have a slice that doesn't have enough indices
	      // to get to a single slice. For example:
	      //    wire [9:0][5:1] foo
	      //      ... foo[4:3] ...
	      // Make this work by finding the indexed slices and
	      // creating a generated slice that spans the whole
	      // range.
	    unsigned long lwid, mwid;
	    bool lrc, mrc;
	    lrc = net->sig()->sb_to_slice(prefix_indices, lsv, sb_lsb, lwid);
	    mrc = net->sig()->sb_to_slice(prefix_indices, msv, sb_msb, mwid);
	    if (!mrc || !lrc) {
		  cerr << get_fileline() << ": error: ";
		  cerr << "Part-select [" << msv << ":" << lsv;
		  cerr << "] exceeds the declared bounds for ";
		  cerr << net->sig()->name();
		  if (net->sig()->unpacked_dimensions() > 0) cerr << "[]";
		  cerr << "." << endl;
		  des->errors += 1;
		  return 0;
	    }
	    ivl_assert(*this, lwid == mwid);
	    sb_msb += mwid - 1;
      } else {
	      // This case, the prefix indices are enough to index
	      // down to a single bit/slice.
	    ivl_assert(*this, prefix_indices.size()+1 == net->sig()->packed_dims().size());
	    sb_lsb = net->sig()->sb_to_idx(prefix_indices, lsv);
	    sb_msb = net->sig()->sb_to_idx(prefix_indices, msv);
      }

      if (sb_msb < sb_lsb) {
	    cerr << get_fileline() << ": error: part select " << net->name();
	    if (net->word_index()) cerr << "[]";
	    cerr << "[" << msv << ":" << lsv << "] is out of order." << endl;
	    des->errors += 1;
	      //delete lsn;
	      //delete msn;
	    return net;
      }

      if (warn_ob_select) {
	    if ((sb_lsb >= (signed) net->vector_width()) ||
	        (sb_msb >= (signed) net->vector_width())) {
		  cerr << get_fileline() << ": warning: "
		          "Part select " << "[" << msv << ":" << lsv
		       << "] is selecting after the ";
		  if (net->word_index()) cerr << "array word ";
		  else cerr << "vector ";
		  cerr << net->name();
		  if (net->word_index()) cerr << "[]";
		  cerr << "[" << net->msi() << ":" << net->lsi() << "]."
		       << endl;
		  cerr << get_fileline() << ":        : "
		       << "Replacing the out of bound bits with 'bx." << endl;
	    }
	    if ((sb_msb < 0) || (sb_lsb < 0)) {
		  cerr << get_fileline() << ": warning: "
		          "Part select " << "[" << msv << ":" << lsv
		       << "] is selecting before the ";
		  if (net->word_index()) cerr << "array word ";
		  else cerr << "vector ";
		  cerr << net->name();
		  if (net->word_index()) cerr << "[]";
		  cerr << "[" << net->msi() << ":" << net->lsi() << "]."
		       << endl;
		  cerr << get_fileline() << ":        : "
		          "Replacing the out of bound bits with 'bx." << endl;
	    }
      }

      unsigned long wid = sb_msb - sb_lsb + 1;

	// If the part select covers exactly the entire
	// vector, then do not bother with it. Return the
	// signal itself, casting to unsigned if necessary.
      if (sb_lsb == 0 && wid == net->vector_width()) {
	    net->cast_signed(false);
	    return net;
      }

	// If the part select covers NONE of the vector, then return a
	// constant X.

      if ((sb_lsb >= (signed) net->vector_width()) || (sb_msb < 0)) {
	    NetEConst*tmp = make_const_x(wid);
	    tmp->set_line(*this);
	    return tmp;
      }

      NetExpr*ex = new NetEConst(verinum(sb_lsb));
      NetESelect*ss = new NetESelect(net, ex, wid);
      ss->set_line(*this);
      return ss;
}

/*
 * Part select indexed up, i.e. net[<m> +: <l>]
 */
NetExpr* PEIdent::elaborate_expr_net_idx_up_(Design*des, NetScope*scope,
				             NetESignal*net, NetScope*,
                                             bool need_const) const
{
      if (net->sig()->data_type() == IVL_VT_STRING) {
	    cerr << get_fileline() << ": error: Cannot take the index part "
	            "select of a string ('" << net->name() << "')." << endl;
	    des->errors += 1;
	    return 0;
      }

      list<long>prefix_indices;
      bool rc = calculate_packed_indices_(des, scope, net->sig(), prefix_indices);
      if (!rc)
	    return 0;

      NetExpr*base = calculate_up_do_base_(des, scope, need_const);
      if (!base)
	    return nullptr;

	// Use the part select width already calculated by test_width().
      unsigned long wid = min_width_;

      if (base->expr_type() == IVL_VT_REAL) {
	    cerr << get_fileline() << ": error: Indexed part select base "
	            "expression for " << net->sig()->name() << "[" << *base
	         << "+:" << wid << "] cannot be a real value." << endl;
	    des->errors += 1;
	    return 0;
      }

	// Handle the special case that the base is constant as
	// well. In this case it can be converted to a conventional
	// part select.
      if (NetEConst*base_c = dynamic_cast<NetEConst*> (base)) {
	    NetExpr*ex;
	    if (base_c->value().is_defined()) {
		  long lsv = base_c->value().as_long();
		  long rel_base = 0;

		    // Check whether an unsigned base fits in a 32 bit int.
		    // This ensures correct results for the vlog95 target, and
		    // for the vvp target on LLP64 platforms (Microsoft Windows).
		  if (!base_c->has_sign() && (int32_t)lsv < 0) {
			  // Return 'bx for a wrapped around base.
			ex = new NetEConst(verinum(verinum::Vx, wid, true));
			ex->set_line(*this);
			delete base;
			if (warn_ob_select) {
			      cerr << get_fileline() << ": warning: " << net->name();
			      if (net->word_index()) cerr << "[]";
			      cerr << "[" << (unsigned long)lsv << "+:" << wid
				   << "] is always outside vector." << endl;
			}
			return ex;
		  }

		    // Get the signal range.
		  const netranges_t&packed = net->sig()->packed_dims();
		  if (prefix_indices.size()+1 < net->sig()->packed_dims().size()) {
			  // Here we are selecting one or more sub-arrays.
			  // Make this work by finding the indexed sub-arrays and
			  // creating a generated slice that spans the whole range.
			unsigned long swid = net->sig()->slice_width(prefix_indices.size()+1);
			ivl_assert(*this, swid > 0);
			long loff, moff;
			unsigned long lwid, mwid;
			bool lrc, mrc;
			mrc = net->sig()->sb_to_slice(prefix_indices, lsv, moff, mwid);
			lrc = net->sig()->sb_to_slice(prefix_indices, lsv+(wid/swid)-1, loff, lwid);
			if (!mrc || !lrc) {
			      cerr << get_fileline() << ": error: ";
			      cerr << "Part-select [" << lsv << "+:" << (wid/swid);
			      cerr << "] exceeds the declared bounds for ";
			      cerr << net->sig()->name();
			      if (net->sig()->unpacked_dimensions() > 0) cerr << "[]";
			      cerr << "." << endl;
			      des->errors += 1;
			      return 0;
			}
			ivl_assert(*this, mwid == swid);
			ivl_assert(*this, lwid == swid);

			if (moff > loff) {
			      rel_base = loff;
			} else {
			      rel_base = moff;
			}
		  } else {
		        long offset = 0;
		          // We want the last range, which is where we work.
		        const netrange_t&rng = packed.back();
		        if (rng.get_msb() < rng.get_lsb()) {
			      offset = -wid + 1;
		        }
		        rel_base = net->sig()->sb_to_idx(prefix_indices, lsv) + offset;
		  }

		    // If the part select covers exactly the entire
		    // vector, then do not bother with it. Return the
		    // signal itself.
		  if (rel_base == 0 && wid == net->vector_width()) {
			delete base;
			net->cast_signed(false);
			return net;
		  }

		    // Otherwise, make a part select that covers the right
		    // range.
		  ex = new NetEConst(verinum(rel_base));
		  if (warn_ob_select) {
			if (rel_base < 0) {
			      cerr << get_fileline() << ": warning: "
			           << net->name();
			      if (net->word_index()) cerr << "[]";
			      cerr << "[" << lsv << "+:" << wid
			           << "] is selecting before vector." << endl;
			}
			if (rel_base + wid > net->vector_width()) {
			      cerr << get_fileline() << ": warning: "
			           << net->name();
			      if (net->word_index()) cerr << "[]";
			      cerr << "[" << lsv << "+:" << wid
			           << "] is selecting after vector." << endl;
			}
		  }
	    } else {
		    // Return 'bx for an undefined base.
		  ex = new NetEConst(verinum(verinum::Vx, wid, true));
		  ex->set_line(*this);
		  delete base;
		  if (warn_ob_select) {
			cerr << get_fileline() << ": warning: " << net->name();
			if (net->word_index()) cerr << "[]";
			cerr << "['bx+:" << wid
			     << "] is always outside vector." << endl;
		  }
		  return ex;
	    }
	    NetESelect*ss = new NetESelect(net, ex, wid);
	    ss->set_line(*this);

	    delete base;
	    return ss;
      }


      ivl_assert(*this, prefix_indices.size()+1 == net->sig()->packed_dims().size());

	// Convert the non-constant part select index expression into
	// an expression that returns a canonical base.
      base = normalize_variable_part_base(prefix_indices, base, net->sig(), wid, true);

      NetESelect*ss = new NetESelect(net, base, wid, IVL_SEL_IDX_UP);
      ss->set_line(*this);

      if (debug_elaborate) {
	    cerr << get_fileline() << ": debug: Elaborate part "
		 << "select base="<< *base << ", wid="<< wid << endl;
      }

      return ss;
}

/*
 * Part select indexed down, i.e. net[<m> -: <l>]
 */
NetExpr* PEIdent::elaborate_expr_net_idx_do_(Design*des, NetScope*scope,
					     NetESignal*net, NetScope*,
                                             bool need_const) const
{
      if (net->sig()->data_type() == IVL_VT_STRING) {
	    cerr << get_fileline() << ": error: Cannot take the index part "
	            "select of a string ('" << net->name() << "')." << endl;
	    des->errors += 1;
	    return 0;
      }

      list<long>prefix_indices;
      bool rc = calculate_packed_indices_(des, scope, net->sig(), prefix_indices);
      if (!rc)
	    return 0;

      NetExpr*base = calculate_up_do_base_(des, scope, need_const);
      if (!base)
	    return nullptr;

	// Use the part select width already calculated by test_width().
      unsigned long wid = min_width_;

      if (base->expr_type() == IVL_VT_REAL) {
	    cerr << get_fileline() << ": error: Indexed part select base "
	            "expression for " << net->sig()->name() << "[" << *base
	         << "-:" << wid << "] cannot be a real value." << endl;
	    des->errors += 1;
	    return 0;
      }

	// Handle the special case that the base is constant as
	// well. In this case it can be converted to a conventional
	// part select.
      if (NetEConst*base_c = dynamic_cast<NetEConst*> (base)) {
	    NetExpr*ex;
	    if (base_c->value().is_defined()) {
		  long lsv = base_c->value().as_long();
		  long rel_base = 0;

		    // Check whether an unsigned base fits in a 32 bit int.
		    // This ensures correct results for the vlog95 target, and
		    // for the vvp target on LLP64 platforms (Microsoft Windows).
		  if (!base_c->has_sign() && (int32_t)lsv < 0) {
			  // Return 'bx for a wrapped around base.
			ex = new NetEConst(verinum(verinum::Vx, wid, true));
			ex->set_line(*this);
			delete base;
			if (warn_ob_select) {
			      cerr << get_fileline() << ": warning: " << net->name();
			      if (net->word_index()) cerr << "[]";
			      cerr << "[" << (unsigned long)lsv << "-:" << wid
				   << "] is always outside vector." << endl;
			}
			return ex;
		  }

		    // Get the signal range.
		  const netranges_t&packed = net->sig()->packed_dims();
		  if (prefix_indices.size()+1 < net->sig()->packed_dims().size()) {
			  // Here we are selecting one or more sub-arrays.
			  // Make this work by finding the indexed sub-arrays and
			  // creating a generated slice that spans the whole range.
			unsigned long swid = net->sig()->slice_width(prefix_indices.size()+1);
			ivl_assert(*this, swid > 0);
			long loff, moff;
			unsigned long lwid, mwid;
			bool lrc, mrc;
			mrc = net->sig()->sb_to_slice(prefix_indices, lsv, moff, mwid);
			lrc = net->sig()->sb_to_slice(prefix_indices, lsv-(wid/swid)+1, loff, lwid);
			if (!mrc || !lrc) {
			      cerr << get_fileline() << ": error: ";
			      cerr << "Part-select [" << lsv << "-:" << (wid/swid);
			      cerr << "] exceeds the declared bounds for ";
			      cerr << net->sig()->name();
			      if (net->sig()->unpacked_dimensions() > 0) cerr << "[]";
			      cerr << "." << endl;
			      des->errors += 1;
			      return 0;
			}
			ivl_assert(*this, mwid == swid);
			ivl_assert(*this, lwid == swid);

			if (moff > loff) {
			      rel_base = loff;
			} else {
			      rel_base = moff;
			}
		  } else {
		        long offset = 0;
		          // We want the last range, which is where we work.
		        const netrange_t&rng = packed.back();
		        if (rng.get_msb() > rng.get_lsb()) {
			      offset = -wid + 1;
		        }
		        rel_base = net->sig()->sb_to_idx(prefix_indices, lsv) + offset;
                  }

		    // If the part select covers exactly the entire
		    // vector, then do not bother with it. Return the
		    // signal itself.
		  if (rel_base == (long)(wid-1) && wid == net->vector_width()) {
			delete base;
			net->cast_signed(false);
			return net;
		  }

		    // Otherwise, make a part select that covers the right
		    // range.
		  ex = new NetEConst(verinum(rel_base));
		  if (warn_ob_select) {
			if (rel_base < 0) {
			      cerr << get_fileline() << ": warning: "
			           << net->name();
			      if (net->word_index()) cerr << "[]";
			      cerr << "[" << lsv << "-:" << wid
			           << "] is selecting before vector." << endl;
			}
			if (rel_base + wid > net->vector_width()) {
			      cerr << get_fileline() << ": warning: "
			           << net->name();
			      if (net->word_index()) cerr << "[]";
			      cerr << "[" << lsv << "-:" << wid
			           << "] is selecting after vector." << endl;
			}
		  }
	    } else {
		    // Return 'bx for an undefined base.
		  ex = new NetEConst(verinum(verinum::Vx, wid, true));
		  ex->set_line(*this);
		  delete base;
		  if (warn_ob_select) {
			cerr << get_fileline() << ": warning: " << net->name();
			if (net->word_index()) cerr << "[]";
			cerr << "['bx-:" << wid
			     << "] is always outside vector." << endl;
		  }
		  return ex;
	    }
	    NetESelect*ss = new NetESelect(net, ex, wid);
	    ss->set_line(*this);

	    delete base;
	    return ss;
      }

      ivl_assert(*this, prefix_indices.size()+1 == net->sig()->packed_dims().size());

	// Convert the non-constant part select index expression into
	// an expression that returns a canonical base.
      base = normalize_variable_part_base(prefix_indices, base, net->sig(), wid, false);

      NetESelect*ss = new NetESelect(net, base, wid, IVL_SEL_IDX_DOWN);
      ss->set_line(*this);

      if (debug_elaborate) {
	    cerr << get_fileline() << ": debug: Elaborate part "
		 << "select base="<< *base << ", wid="<< wid << endl;
      }

      return ss;
}

NetExpr* PEIdent::elaborate_expr_net_bit_(Design*des, NetScope*scope,
				          NetESignal*net, NetScope*,
                                          bool need_const) const
{
      list<long>prefix_indices;
      bool rc = calculate_packed_indices_(des, scope, net->sig(), prefix_indices);
      if (!rc)
	    return 0;

      const name_component_t&name_tail = path_.back();
      ivl_assert(*this, !name_tail.index.empty());

      const index_component_t&index_tail = name_tail.index.back();
      ivl_assert(*this, index_tail.msb != 0);
      ivl_assert(*this, index_tail.lsb == 0);

      NetExpr*mux = elab_and_eval(des, scope, index_tail.msb, -1, need_const);
      if (!mux)
	    return 0;

      if (mux->expr_type() == IVL_VT_REAL) {
	    cerr << get_fileline() << ": error: Index expression for "
	         << net->sig()->name() << "[" << *mux
	         << "] cannot be a real value." << endl;
	    des->errors += 1;
	    return 0;
      }

      if (const netdarray_t*darray = net->sig()->darray_type()) {
	      // Special case: This is a select of a dynamic
	      // array. Generate a NetESelect and attach it to
	      // the NetESignal. This should be interpreted as
	      // an array word select downstream.
	    if (debug_elaborate) {
		  cerr << get_fileline() << ": debug: "
		       << "Bit select of a dynamic array becomes NetESelect." << endl;
	    }
	    NetESelect*res = new NetESelect(net, mux, darray->element_width(), darray->element_type());
	    res->set_line(*net);
	    return res;
      }

	// If the bit select is constant, then treat it similar
	// to the part select, so that I save the effort of
	// making a mux part in the netlist.
      if (NetEConst*msc = dynamic_cast<NetEConst*> (mux)) {

	    if (debug_elaborate) {
		  cerr << get_fileline() << ": PEIdent::elaborate_expr_net_bit_: "
		       << "mux is constant=" << *msc
		       << ", packed_dims()=" << net->sig()->packed_dims()
		       << ", packed_dims().size()=" << net->sig()->packed_dims().size()
		       << ", prefix_indices.size()=" << prefix_indices.size()
		       << endl;
	    }

	      // Special case: The bit select expression is constant
	      // x/z. The result of the expression is 1'bx.
	    if (! msc->value().is_defined()) {
		  if (warn_ob_select) {
			cerr << get_fileline() << ": warning: "
			        "Constant bit select [" << msc->value()
			      << "] is undefined for ";
			if (net->word_index()) cerr << "array word";
			else cerr << "vector";
			cerr << " '" << net->name();
			if (net->word_index()) cerr << "[]";
			cerr  << "'." << endl;
			cerr << get_fileline() << ":        : "
			     << "Replacing select with a constant 1'bx."
			     << endl;
		  }

		    // FIXME: Should I be using slice_width() here?
		  NetEConst*tmp = make_const_x(1);
		  tmp->set_line(*this);
		  delete mux;
		  return tmp;
	    }

	    long msv = msc->value().as_long();

	    const netranges_t& sig_packed = net->sig()->packed_dims();
	    if (prefix_indices.size()+2 <= sig_packed.size()) {
		    // Special case: this is a slice of a multi-dimensional
		    // packed array. For example:
		    //   reg [3:0][7:0] x;
		    //   ... x[2] ...
		    // This shows up as the prefix_indices being too short
		    // for the packed dimensions of the vector. What we do
		    // here is convert to a "slice" of the vector.
		  unsigned long lwid;
		  long idx;
		  rc = net->sig()->sb_to_slice(prefix_indices, msv, idx, lwid);

                  if(!rc) {
                    cerr << get_fileline() << ": error: Index " << net->sig()->name()
                         << "[" << msv << "] is out of range."
                         << endl;
                    des->errors += 1;
                    return 0;
                  }

		    // Make an expression out of the index
		  NetEConst*idx_c = new NetEConst(verinum(idx));
		  idx_c->set_line(*net);

		  NetESelect*res = new NetESelect(net, idx_c, lwid);
		  res->set_line(*net);
		  return res;
	    }

	    if (net->sig()->data_type()==IVL_VT_STRING && (msv < 0)) {
		    // Special case: This is a constant bit select of
		    // a string, and the index is < 0. For example:
		    //   string foo;
		    //   ... foo[-1] ...
		    // This is known to be 8'h00.
		  NetEConst*tmp = make_const_0(8);
		  tmp->set_line(*this);
		  delete mux;
		  return tmp;
	    }

	    if (net->sig()->data_type()==IVL_VT_STRING) {
		    // Special case: This is a select of a string
		    // variable. Generate a NetESelect and attach it
		    // to the NetESignal. This should be interpreted
		    // as a character select downstream.
		  if (debug_elaborate) {
			cerr << get_fileline() << ": debug: "
			     << "Bit select of string becomes NetESelect." << endl;
		  }
		  NetESelect*res = new NetESelect(net, mux, 8);
		  res->set_line(*net);
		  return res;
	    }

	    long idx = net->sig()->sb_to_idx(prefix_indices,msv);

	    if (idx >= (long)net->vector_width() || idx < 0) {
		    /* The bit select is out of range of the
		       vector. This is legal, but returns a
		       constant 1'bx value. */
		  if (warn_ob_select) {
			cerr << get_fileline() << ": warning: "
			        "Constant bit select [" << msv
			      << "] is ";
			if (idx < 0) cerr << "before ";
			else cerr << "after ";
			if (net->word_index()) cerr << "array word ";
			else cerr << "vector ";
			cerr << net->name();
			if (net->word_index()) cerr << "[]";
			cerr  << net->sig()->packed_dims() << "." << endl;
			cerr << get_fileline() << ":        : "
			     << "Replacing select with a constant 1'bx."
			     << endl;
		  }

		  NetEConst*tmp = make_const_x(1);
		  tmp->set_line(*this);

		  delete mux;
		  return tmp;
	    }

	      // If the vector is only one bit, we are done. The
	      // bit select will return the scalar itself.
	    if (net->vector_width() == 1)
		  return net;

	    if (debug_elaborate) {
		  cerr << get_fileline() << ": PEIdent::elaborate_expr_net_bit_: "
		       << "Make bit select idx=" << idx
		       << endl;
	    }

	      // Make an expression out of the index
	    NetEConst*idx_c = new NetEConst(verinum(idx));
	    idx_c->set_line(*net);

	      // Make a bit select with the canonical index
	    NetESelect*res = new NetESelect(net, idx_c, 1);
	    res->set_line(*net);

	    return res;
      }

      const netranges_t& sig_packed = net->sig()->packed_dims();
      if (prefix_indices.size()+2 <= sig_packed.size()) {
	      // Special case: this is a slice of a multi-dimensional
	      // packed array. For example:
	      //   reg [3:0][7:0] x;
	      //   x[2] = ...
	      // This shows up as the prefix_indices being too short
	      // for the packed dimensions of the vector. What we do
	      // here is convert to a "slice" of the vector.
	    unsigned long lwid;
	    mux = normalize_variable_slice_base(prefix_indices, mux,
						net->sig(), lwid);
	    mux->set_line(*net);

	      // Make a PART select with the canonical index
	    NetESelect*res = new NetESelect(net, mux, lwid);
	    res->set_line(*net);

	    return res;
      }

      if (net->sig()->data_type() == IVL_VT_STRING) {
	      // Special case: This is a select of a string.
	      // This should be interpreted as a byte select.
	    if (debug_elaborate) {
		  cerr << get_fileline() << ": debug: "
		       << "Bit select of a string becomes NetESelect." << endl;
	    }
	    NetESelect*res = new NetESelect(net, mux, 8);
	    res->set_line(*net);
	    return res;
      }

	// Non-constant bit select? punt and make a subsignal
	// device to mux the bit in the net. This is a fairly
	// complicated task because we need to generate
	// expressions to convert calculated bit select
	// values to canonical values that are used internally.
      mux = normalize_variable_bit_base(prefix_indices, mux, net->sig());

      NetESelect*ss = new NetESelect(net, mux, 1);
      ss->set_line(*this);
      return ss;
}

NetExpr* PEIdent::elaborate_expr_net_bit_last_(Design*, NetScope*,
					       NetESignal*net,
					       NetScope* /* found_in */,
					       bool need_const) const
{
      if (need_const) {
	    cerr << get_fileline() << ": error: "
		 << "Expression with \"[$]\" is not constant." << endl;
	    return 0;
      }

      unsigned use_width = 1;
      ivl_type_t use_type = 0;
      if (const netdarray_t*darray = net->sig()->darray_type()) {
	    use_width = darray->element_width();
	    use_type = darray->element_type();
      }

      NetELast*mux = new NetELast(net->sig());
      mux->set_line(*this);
      NetESelect*ss = new NetESelect(net, mux, use_width, use_type);
      ss->set_line(*this);
      return ss;
}

NetExpr* PEIdent::elaborate_expr_net(Design*des, NetScope*scope,
				     NetNet*net, NetScope*found_in,
                                     unsigned expr_wid,
				     unsigned flags) const
{
      if (debug_elaborate) {
	    cerr << get_fileline() << ": PEIdent::elaborate_expr_net: "
		 << "net=" << net->name()
		 << ", net->unpacked_dimensions()=" << net->unpacked_dimensions()
		 << ", net->get_scalar()=" << (net->get_scalar()?"true":"false")
		 << ", net->net_type()=" << *net->net_type()
		 << endl;
      }

      if (net->unpacked_dimensions() > 0)
	    return elaborate_expr_net_word_(des, scope, net, found_in,
                                            expr_wid, flags);

      bool need_const = NEED_CONST & flags;

      NetESignal*node = new NetESignal(net);
      node->set_line(*this);

      index_component_t::ctype_t use_sel = index_component_t::SEL_NONE;
      if (! path_.name.back().index.empty())
	    use_sel = path_.name.back().index.back().sel;

      if (net->get_scalar() && use_sel != index_component_t::SEL_NONE) {
	    cerr << get_fileline() << ": error: can not select part of ";
	    if (node->expr_type() == IVL_VT_REAL) cerr << "real: ";
	    else cerr << "scalar: ";
	    cerr << net->name() << endl;
	    des->errors += 1;
	    return 0;
      }

      list<long> prefix_indices;
      bool rc = evaluate_index_prefix(des, scope, prefix_indices, path_.back().index);
      if (!rc) return 0;

	// If this is a part select of a signal, then make a new
	// temporary signal that is connected to just the
	// selected bits. The lsb_ and msb_ expressions are from
	// the foo[msb:lsb] expression in the original.
      if (use_sel == index_component_t::SEL_PART)
	    return elaborate_expr_net_part_(des, scope, node, found_in,
                                            expr_wid);

      if (use_sel == index_component_t::SEL_IDX_UP)
	    return elaborate_expr_net_idx_up_(des, scope, node, found_in,
                                              need_const);

      if (use_sel == index_component_t::SEL_IDX_DO)
	    return elaborate_expr_net_idx_do_(des, scope, node, found_in,
                                              need_const);

      if (use_sel == index_component_t::SEL_BIT)
	    return elaborate_expr_net_bit_(des, scope, node, found_in,
                                           need_const);

      if (use_sel == index_component_t::SEL_BIT_LAST)
	    return elaborate_expr_net_bit_last_(des, scope, node, found_in,
						need_const);

	// It's not anything else, so this must be a simple identifier
	// expression with no part or bit select. Return the signal
	// itself as the expression.
      ivl_assert(*this, use_sel == index_component_t::SEL_NONE);

      return node;
}

unsigned PENewArray::test_width(Design*, NetScope*, width_mode_t&)
{
      expr_type_  = IVL_VT_DARRAY;
      expr_width_ = 1;
      min_width_  = 1;
      signed_flag_= false;
      return 1;
}

NetExpr* PENewArray::elaborate_expr(Design*des, NetScope*scope,
				    ivl_type_t ntype, unsigned flags) const
{
	// Elaborate the size expression.
      width_mode_t mode = LOSSLESS;
      unsigned use_wid = size_->test_width(des, scope, mode);
      NetExpr*size = size_->elaborate_expr(des, scope, use_wid, flags);
      NetExpr*init_val = 0;

      if (dynamic_cast<PEAssignPattern*> (init_)) {
	      // Special case: the initial value expression is an
	      // array_pattern. Elaborate the expression like the
	      // r-value to an assignment to array.
	    init_val = init_->elaborate_expr(des, scope, ntype, flags);

      } else if (init_) {
	      // Regular case: The initial value is an
	      // expression. Elaborate the expression as an element
	      // type. The run-time will assign this value to each element.
	    const netarray_t*array_type = dynamic_cast<const netarray_t*> (ntype);

	    init_val = init_->elaborate_expr(des, scope, array_type, flags);
      }

      NetENew*tmp = new NetENew(ntype, size, init_val);
      tmp->set_line(*this);

      return tmp;
}

NetExpr* PENewArray::elaborate_expr(Design*des, NetScope*, unsigned, unsigned) const
{
      cerr << get_fileline() << ": error: The new array constructor may "
              "only be used in an assignment to a dynamic array." << endl;
      des->errors += 1;
      return 0;
}

unsigned PENewClass::test_width(Design*, NetScope*, width_mode_t&)
{
      expr_type_  = IVL_VT_CLASS;
      expr_width_ = 1;
      min_width_  = 1;
      signed_flag_= false;
      return 1;
}

/*
 * This elaborates the constructor for a class. This arranges for the
 * call of class constructor, if present, and also
 * initializers in front of an explicit constructor.
 *
 * The derived argument is the type of the class derived from the
 * current one. This is used to get chained constructor arguments, if necessary.
 */
NetExpr* PENewClass::elaborate_expr_constructor_(Design*des, NetScope*scope,
						 const netclass_t*ctype,
						 NetExpr*obj, unsigned /*flags*/) const
{
      ivl_assert(*this, ctype);

      NetScope *new_scope = ctype->get_constructor();
      if (new_scope == 0) {
	      // No constructor.
	    if (parms_.size() > 0) {
		  cerr << get_fileline() << ": error: "
		       << "Class " << ctype->get_name()
		       << " has no constructor, but you passed " << parms_.size()
		       << " arguments to the new operator." << endl;
		  des->errors += 1;
	    }
	    return obj;
      }


      NetFuncDef*def = new_scope->func_def();
      if (def == 0) {
	    cerr << get_fileline() << ": internal error: "
		 << "Scope " << scope_path(new_scope)
		 << " is missing constructor definition." << endl;
	    des->errors += 1;
      }
      ivl_assert(*this, def);

	// Are there too many arguments passed to the function. If so,
	// generate an error message. The case of too few arguments
	// will be handled below, when we run out of arguments.
      if ((parms_.size()+1) > def->port_count()) {
	    cerr << get_fileline() << ": error: Argument count mismatch."
		 << " Passing " << parms_.size() << " arguments"
		 << " to constructor expecting " << (def->port_count()-1)
		 << " arguments." << endl;
	    des->errors += 1;
      }

      vector<NetExpr*> parms (def->port_count());
      parms[0] = obj;

      auto args = map_named_args(des, def, parms_, 1);

      int missing_parms = 0;
      for (size_t idx = 1 ; idx < parms.size() ; idx += 1) {
	      // While there are default arguments, check them.
	    if (args[idx - 1]) {
		  parms[idx] = elaborate_rval_expr(des, scope,
						   def->port(idx)->net_type(),
						   args[idx - 1], false);
		  // NOTE: if elaborate_rval_expr fails, it will return a
		  // nullptr, but it will also increment des->errors so there
		  // is nothing we need to do here.

		  continue;
	    }

	      // Ran out of explicit arguments. Is there a default
	      // argument we can use?
	    if (NetExpr*tmp = def->port_defe(idx)) {
		  parms[idx] = tmp->dup_expr();
		  continue;
	    }

	      // If we run out of passed expressions, and there is no
	      // default value for this port, then we will need to
	      // report an error that we are missing parameters.
	    missing_parms += 1;
	    parms[idx] = 0;
      }

      if (missing_parms > 0) {
	    cerr << get_fileline() << ": error: The " << scope_path(new_scope)
		 << " constructor call is missing arguments." << endl;
	    des->errors += 1;
      }

	// The return value for the constructor is actually the "this"
	// variable, instead of the "new" scope name.
      NetNet*res = new_scope->find_signal(perm_string::literal(THIS_TOKEN));
      ivl_assert(*this, res);

      NetESignal*eres = new NetESignal(res);
      NetEUFunc*con = new NetEUFunc(scope, new_scope, eres, parms, true);
      con->set_line(*this);

      return con;
}

NetExpr* PENewClass::elaborate_expr(Design*des, NetScope*scope,
				    ivl_type_t ntype, unsigned flags) const
{
	// Find the constructor for the class. If there is no
	// constructor then the result of this expression is the
	// allocation alone.
      const netclass_t*ctype = dynamic_cast<const netclass_t*> (ntype);

      if (!ctype) {
	    cerr << get_fileline() << ": error: class new not allowed here. "
		 << "Left-hand side is not of class type." << endl;
	    des->errors++;
	    return 0;
      }

      if (class_type_) {
	    ivl_type_t elab_class_type = class_type_->elaborate_type(des,
								     scope);
	    ctype = dynamic_cast<const netclass_t*> (elab_class_type);
	    if (!ctype) {
		  cerr << get_fileline() << ": error: Incompatible type in"
		       << " typed constructor call.\n"
		       << get_fileline() << ":      : Constructor type `"
		       << *elab_class_type << "` is not a class type."
		       << endl;
		  des->errors++;
		  return nullptr;
	    }

	    if (!ntype->type_compatible(ctype)) {
		  cerr << get_fileline() << ": error: Incompatible type in"
		       << " typed constructor call.\n"
		       << get_fileline() << ":      : Constructor type `"
		       << *ctype
		       << "` is not compatible with the target type `"
		       << *ntype << "`." << endl;
		  des->errors++;
		  return nullptr;
	    }
      }

      if (ctype->is_virtual()) {
	    cerr << get_fileline() << ": error: "
	         << "Can not create object of virtual class `"
		 << ctype->get_name() << "`." << endl;
	    des->errors++;
	    return 0;
      }

      NetExpr*obj = new NetENew(ctype);
      obj->set_line(*this);

      obj = elaborate_expr_constructor_(des, scope, ctype, obj, flags);
      return obj;
}

unsigned PENewCopy::test_width(Design*, NetScope*, width_mode_t&)
{
      expr_type_  = IVL_VT_CLASS;
      expr_width_ = 1;
      min_width_  = 1;
      signed_flag_= false;
      return 1;
}

NetExpr* PENewCopy::elaborate_expr(Design*des, NetScope*scope, ivl_type_t obj_type, unsigned) const
{
      NetExpr*copy_arg = src_->elaborate_expr(des, scope, obj_type, 0);
      if (copy_arg == 0)
	    return 0;

      NetENew*obj_new = new NetENew(obj_type);
      obj_new->set_line(*this);

      NetEShallowCopy*copy = new NetEShallowCopy(obj_new, copy_arg);
      copy->set_line(*this);

      return copy;
}

/*
 * A "null" expression represents class objects/handles. This brings
 * up a ton of special cases, but we handle it here by setting the
 * expr_type_ and expr_width_ to fixed values.
 */
unsigned PENull::test_width(Design*, NetScope*, width_mode_t&)
{
      expr_type_   = IVL_VT_CLASS;
      expr_width_  = 1;
      min_width_   = 1;
      signed_flag_ = false;
      return expr_width_;
}

NetExpr* PENull::elaborate_expr(Design*, NetScope*, ivl_type_t, unsigned) const
{
      NetENull*tmp = new NetENull;
      tmp->set_line(*this);
      return tmp;
}

NetExpr* PENull::elaborate_expr(Design*, NetScope*, unsigned, unsigned) const
{
      NetENull*tmp = new NetENull;
      tmp->set_line(*this);
      return tmp;
}

unsigned PENumber::test_width(Design*, NetScope*, width_mode_t&mode)
{
      expr_type_   = IVL_VT_LOGIC;
      expr_width_  = value_->len();
      min_width_   = expr_width_;
      signed_flag_ = value_->has_sign();

      if (!value_->has_len() && !value_->is_single()) {
            if (gn_strict_expr_width_flag) {
                  expr_width_ = integer_width;
                  mode = UNSIZED;
            } else if (mode < LOSSLESS) {
		  if (expr_width_ < integer_width) {
			expr_width_ = integer_width;
			if (mode < UNSIZED)
			      mode = UNSIZED;
		  } else {
			mode = LOSSLESS;
		  }
            }
      }

      if (debug_elaborate) {
	    cerr << get_fileline() << ": PENumber::test_width: "
		 << "Value=" << *value_
		 << ", width=" << expr_width_
		 << ", output mode=" << width_mode_name(mode) << endl;
      }

      return expr_width_;
}

NetExpr* PENumber::elaborate_expr(Design*, NetScope*, ivl_type_t ntype, unsigned) const
{
      if (debug_elaborate) {
	    cerr << get_fileline() << ": PENumber::elaborate_expr: "
		 << "expression: " << *this << endl;
	    if (ntype)
		  cerr << get_fileline() << ": PENumber::elaborate_expr: "
		       << "ntype=" << *ntype << endl;
      }

      // Icarus allows dynamic arrays to be initialised with a single value.
      if (const netdarray_t*array_type = dynamic_cast<const netdarray_t*> (ntype))
            ntype = array_type->element_type();

      // Special case: If the context type is REAL, then cast the
      // vector value to a real and return a NetECReal.
      if (ntype->base_type() == IVL_VT_REAL) {
	    verireal val (value_->as_long());
	    NetECReal*tmp = new NetECReal(val);
	    tmp->set_line(*this);
	    return tmp;
      }

      verinum use_val = value();
      use_val.has_sign( ntype->get_signed() );
      use_val = cast_to_width(use_val, ntype->packed_width());

      NetEConst*tmp = new NetEConst(use_val);
      tmp->set_line(*this);

      return tmp;
}

NetEConst* PENumber::elaborate_expr(Design*, NetScope*,
				    unsigned expr_wid, unsigned) const
{
      ivl_assert(*this, value_);
      verinum val = *value_;
      if (val.has_len())
            val.has_sign(signed_flag_);
      val = cast_to_width(val, expr_wid);
      NetEConst*tmp = new NetEConst(val);
      tmp->cast_signed(signed_flag_);
      tmp->set_line(*this);

      return tmp;
}

unsigned PEString::test_width(Design*, NetScope*, width_mode_t&)
{
      expr_type_   = IVL_VT_BOOL;
      expr_width_  = text_ ? verinum(text_).len() : 0;
      min_width_   = expr_width_;
      signed_flag_ = false;

      return expr_width_;
}

NetEConst* PEString::elaborate_expr(Design*, NetScope*, ivl_type_t, unsigned) const
{
      NetECString*tmp = new NetECString(value());
      tmp->cast_signed(signed_flag_);
      tmp->set_line(*this);

      return tmp;
}

/*
 * When the expression is being elaborated with a width, then we are trying to
 * make a vector, so create a NetEConst with the basic types.
 */
NetEConst* PEString::elaborate_expr(Design*, NetScope*,
				    unsigned expr_wid, unsigned) const
{
      verinum val(value());
      val = pad_to_width(val, expr_wid);
      NetEConst*tmp = new NetEConst(val);
      tmp->cast_signed(signed_flag_);
      tmp->set_line(*this);

      return tmp;
}

unsigned PETernary::test_width(Design*des, NetScope*scope, width_mode_t&mode)
{
	// The condition of the ternary is self-determined, so
	// we will test its width when we elaborate it.

        // Test the width of the true and false clauses.
      unsigned tru_width = tru_->test_width(des, scope, mode);

      width_mode_t saved_mode = mode;

      unsigned fal_width = fal_->test_width(des, scope, mode);

        // If the width mode changed, retest the true clause, as it
        // may choose a different width if it is in a lossless context.
      if ((mode >= LOSSLESS) && (saved_mode < LOSSLESS)) {
	    tru_width = tru_->test_width(des, scope, mode);
      }

	// If either of the alternatives is IVL_VT_REAL, then the
	// expression as a whole is IVL_VT_REAL. Otherwise, if either
	// of the alternatives is IVL_VT_LOGIC, then the expression as
	// a whole is IVL_VT_LOGIC. The fallback assumes that the
	// types are the same and we take that.
      ivl_variable_type_t tru_type = tru_->expr_type();
      ivl_variable_type_t fal_type = fal_->expr_type();

      if (tru_type == IVL_VT_REAL || fal_type == IVL_VT_REAL) {
	    expr_type_ = IVL_VT_REAL;
      } else if (tru_type == IVL_VT_LOGIC || fal_type == IVL_VT_LOGIC) {
	    expr_type_ = IVL_VT_LOGIC;
      } else {
	    expr_type_ = tru_type;
      }
      if (expr_type_ == IVL_VT_REAL) {
	    expr_width_  = 1;
            min_width_   = 1;
            signed_flag_ = true;
      } else {
	    expr_width_  = max(tru_width, fal_width);
            min_width_   = max(tru_->min_width(), fal_->min_width());
            signed_flag_ = tru_->has_sign() && fal_->has_sign();

              // If the alternatives are different types, the expression
              // is forced to unsigned. In this case the lossless width
              // calculation is unreliable and we need to make sure the
              // final expression width is at least integer_width.
            if ((mode == LOSSLESS) && (tru_->has_sign() != fal_->has_sign()))
                  mode = UPSIZE;
      }

      if (debug_elaborate)
	    cerr << get_fileline() << ": debug: "
		 << "Ternary expression type=" << expr_type_
		 << ", width=" << expr_width_
		 << " (tru_type=" << tru_type
		 << ", fal_type=" << fal_type << ")" << endl;

      return fix_width_(mode);
}

bool NetETernary::test_operand_compat(ivl_variable_type_t l,
				      ivl_variable_type_t r)
{
      if (l == IVL_VT_LOGIC && r == IVL_VT_BOOL)
	    return true;
      if (l == IVL_VT_BOOL && r == IVL_VT_LOGIC)
	    return true;

      if (l == IVL_VT_REAL && (r == IVL_VT_LOGIC || r == IVL_VT_BOOL))
	    return true;
      if (r == IVL_VT_REAL && (l == IVL_VT_LOGIC || l == IVL_VT_BOOL))
	    return true;

      if (l == r)
	    return true;

      return false;
}

/*
 * Elaborate the Ternary operator. I know that the expressions were
 * parsed so I can presume that they exist, and call elaboration
 * methods. If any elaboration fails, then give up and return 0.
 */
NetExpr*PETernary::elaborate_expr(Design*des, NetScope*scope,
				  unsigned expr_wid, unsigned flags) const
{
      flags &= ~SYS_TASK_ARG; // don't propagate the SYS_TASK_ARG flag

      ivl_assert(*this, expr_);
      ivl_assert(*this, tru_);
      ivl_assert(*this, fal_);

	// Elaborate and evaluate the condition expression. Note that
	// it is always self-determined.
      NetExpr*con = elab_and_eval(des, scope, expr_, -1, NEED_CONST & flags);
      if (con == 0)
	    return 0;

	/* Make sure the condition expression reduces to a single bit. */
      con = condition_reduce(con);

	// Verilog doesn't say that we must do short circuit evaluation
	// of ternary expressions, but it doesn't disallow it.
      if (NetEConst*tmp = dynamic_cast<NetEConst*> (con)) {
	    verinum cval = tmp->value();
	    ivl_assert(*this, cval.len()==1);

	      // Condition is constant TRUE, so we only need the true clause.
	    if (cval.get(0) == verinum::V1) {
		  if (debug_elaborate)
			cerr << get_fileline() << ": debug: Short-circuit "
			        "elaborate TRUE clause of ternary."
			     << endl;

		    // Evaluate the alternate expression to find any errors.
		  NetExpr*dmy = elab_and_eval_alternative_(des, scope, fal_,
		                                           expr_wid, flags,
		                                           true);
		  delete dmy;

		  delete con;
		  return elab_and_eval_alternative_(des, scope, tru_,
                                                    expr_wid, flags, true);
	    }

	      // Condition is constant FALSE, so we only need the
	      // false clause.
	    if (cval.get(0) == verinum::V0) {
		  if (debug_elaborate)
			cerr << get_fileline() << ": debug: Short-circuit "
			        "elaborate FALSE clause of ternary."
			<< endl;

		    // Evaluate the alternate expression to find any errors.
		  NetExpr*dmy = elab_and_eval_alternative_(des, scope, tru_,
		                                           expr_wid, flags,
		                                           true);
		  delete dmy;

		  delete con;
		  return elab_and_eval_alternative_(des, scope, fal_,
                                                    expr_wid, flags, true);
	    }

	      // X and Z conditions need to blend both results, so we
	      // can't short-circuit.
      }

      NetExpr*tru = elab_and_eval_alternative_(des, scope, tru_,
					       expr_wid, flags, false);
      if (tru == 0) {
	    delete con;
	    return 0;
      }

      NetExpr*fal = elab_and_eval_alternative_(des, scope, fal_,
					       expr_wid, flags, false);
      if (fal == 0) {
	    delete con;
	    delete tru;
	    return 0;
      }

      if (! NetETernary::test_operand_compat(tru->expr_type(), fal->expr_type())) {
	    cerr << get_fileline() << ": error: Data types "
		 << tru->expr_type() << " and "
		 << fal->expr_type() << " of ternary"
		 << " do not match." << endl;
	    des->errors += 1;
	    return 0;
      }

      NetETernary*res = new NetETernary(con, tru, fal, expr_wid, signed_flag_);
      res->set_line(*this);
      return res;
}

/*
 * When elaborating the true or false alternative expression of a
 * ternary, take into account the overall expression type. If the type
 * is not vectorable, then the alternative expression is evaluated as
 * self-determined.
 */
NetExpr* PETernary::elab_and_eval_alternative_(Design*des, NetScope*scope,
					       PExpr*expr, unsigned expr_wid,
                                               unsigned flags, bool short_cct) const
{
      int context_wid = expr_wid;
      if (type_is_vectorable(expr->expr_type()) && !type_is_vectorable(expr_type_)) {
	    expr_wid = expr->expr_width();
            context_wid = -1;
      } else {
            expr->cast_signed(signed_flag_);
      }
      NetExpr*tmp = expr->elaborate_expr(des, scope, expr_wid, flags);
      if (tmp == 0) return 0;

      if (short_cct && (expr_type_ == IVL_VT_REAL)
          && (expr->expr_type() != IVL_VT_REAL))
	    tmp = cast_to_real(tmp);

      eval_expr(tmp, context_wid);

      return tmp;
}

/*
 * A typename expression is only legal in very narrow cases. This is
 * just a placeholder.
 */
unsigned PETypename::test_width(Design*des, NetScope*, width_mode_t&)
{
      cerr << get_fileline() << ": error: "
	   << "Type names are not valid expressions here." << endl;
      des->errors += 1;

      expr_type_   = IVL_VT_NO_TYPE;
      expr_width_  = 1;
      min_width_   = 1;
      signed_flag_ = false;
      return expr_width_;
}

NetExpr*PETypename::elaborate_expr(Design*des, NetScope*,
				   ivl_type_t, unsigned) const
{
      cerr << get_fileline() << ": error: Type name not a valid expression here." << endl;
      des->errors += 1;
      return 0;
}

unsigned PEUnary::test_width(Design*des, NetScope*scope, width_mode_t&mode)
{
	// Evaluate the expression width to get the correct type information
      expr_width_  = expr_->test_width(des, scope, mode);

      if (expr_->expr_type() == IVL_VT_CLASS) {
	    cerr << get_fileline() << ": error: "
	    << "Class/null is not allowed with the '"
	    << human_readable_op(op_) << "' operator." << endl;
	    des->errors += 1;
      }

      switch (op_) {
	  case '&': // Reduction AND
	  case '|': // Reduction OR
	  case '^': // Reduction XOR
	  case 'A': // Reduction NAND (~&)
	  case 'N': // Reduction NOR (~|)
	  case 'X': // Reduction NXOR (~^)
	  case '!':
	    {
		  width_mode_t sub_mode = SIZED;
		  unsigned sub_width = expr_->test_width(des, scope, sub_mode);

		  expr_type_   = expr_->expr_type();
	          expr_width_  = 1;
	          min_width_   = 1;
                  signed_flag_ = false;

                  if ((op_ == '!') && (expr_type_ != IVL_VT_BOOL))
                        expr_type_ = IVL_VT_LOGIC;

		  if (debug_elaborate)
			cerr << get_fileline() << ": debug: "
			     << "Test width of sub-expression of " << op_
			     << " returns " << sub_width << "." << endl;

	    }
            return expr_width_;
      }

      expr_type_   = expr_->expr_type();
      min_width_   = expr_->min_width();
      signed_flag_ = expr_->has_sign();

      return fix_width_(mode);
}


NetExpr* PEUnary::elaborate_expr(Design*des, NetScope*scope,
				 unsigned expr_wid, unsigned flags) const
{
      flags &= ~SYS_TASK_ARG; // don't propagate the SYS_TASK_ARG flag
      ivl_variable_type_t t;

      unsigned sub_width = expr_wid;
      switch (op_) {
            // Reduction operators and ! always have a self determined width.
	  case '!':
	  case '&': // Reduction AND
	  case '|': // Reduction OR
	  case '^': // Reduction XOR
	  case 'A': // Reduction NAND (~&)
	  case 'N': // Reduction NOR (~|)
	  case 'X': // Reduction NXOR (~^)
	    sub_width = expr_->expr_width();
	    break;

            // Other operators have context determined operands, so propagate
            // the expression type (signed/unsigned) down to the operands.
	  default:
            expr_->cast_signed(signed_flag_);
	    break;
      }
      NetExpr*ip = expr_->elaborate_expr(des, scope, sub_width, flags);
      if (ip == 0) return 0;

      ivl_assert(*expr_, expr_type_ != IVL_VT_NO_TYPE);

      NetExpr*tmp;
      switch (op_) {
	  case 'i':
	  case 'I':
	  case 'D':
	  case 'd':
		t = ip->expr_type();
		if (expr_wid != expr_->expr_width()) {
			/*
			 * TODO: Need to modify draw_unary_expr() to support
			 * increment/decrement operations on slice of vector.
			 */
			cerr << get_fileline() << ": sorry: "
				<< human_readable_op(op_, true)
				<< " operation is not yet supported on "
				<< "vector slice." << endl;
			des->errors += 1;
			return 0;
		} else if (t == IVL_VT_LOGIC || t == IVL_VT_BOOL ||
				t == IVL_VT_REAL) {

			if (dynamic_cast<NetEConst *> (ip) ||
				dynamic_cast<NetECReal*> (ip)) {
				/*
				 * invalid operand: operand is a constant
				 * or real number
				 */
				cerr << get_fileline() << ": error: "
					<< "inappropriate use of "
					<< human_readable_op(op_, true)
					<< " operator." << endl;
				des->errors += 1;
				return 0;
			}

			/*
			 * **** Valid use of operator ***
			 * For REAL variables draw_unary_real() is invoked during
			 * evaluation and for LOGIC/BOOLEAN draw_unary_expr()
			 * is called for evaluation.
			 */
			tmp = new NetEUnary(op_, ip, expr_wid, signed_flag_);
			tmp->set_line(*this);
		} else {
			cerr << get_fileline() << ": error: "
				<< "inappropriate use of "
				<< human_readable_op(op_, true)
				<< " operator." << endl;
			des->errors += 1;
			return 0;
		}
		break;

	  default:
	    tmp = new NetEUnary(op_, ip, expr_wid, signed_flag_);
	    tmp->set_line(*this);
	    break;

	  case '-':
	    if (NetEConst*ipc = dynamic_cast<NetEConst*>(ip)) {

		  verinum val = - ipc->value();
		  tmp = new NetEConst(val);
		  tmp->cast_signed(signed_flag_);
		  tmp->set_line(*this);
		  delete ip;

	    } else if (NetECReal*ipr = dynamic_cast<NetECReal*>(ip)) {

		    /* When taking the - of a real, fold this into the
		       constant value. */
		  verireal val = - ipr->value();
		  tmp = new NetECReal(val);
		  tmp->set_line(*this);
		  delete ip;

	    } else {
		  tmp = new NetEUnary(op_, ip, expr_wid, signed_flag_);
		  tmp->set_line(*this);
	    }
	    break;

	  case '+':
	    tmp = ip;
	    break;

	  case '!': // Logical NOT
	      /* If the operand to unary ! is a constant, then I can
		 evaluate this expression here and return a logical
		 constant in its place. */
	    if (NetEConst*ipc = dynamic_cast<NetEConst*>(ip)) {
		  verinum val = ipc->value();
		  unsigned v1 = 0;
		  unsigned vx = 0;
		  for (unsigned idx = 0 ;  idx < val.len() ;  idx += 1)
			switch (val[idx]) {
			    case verinum::V0:
			      break;
			    case verinum::V1:
			      v1 += 1;
			      break;
			    default:
			      vx += 1;
			      break;
			}

		  verinum::V res;
		  if (v1 > 0)
			res = verinum::V0;
		  else if (vx > 0)
			res = verinum::Vx;
		  else
			res = verinum::V1;

		  verinum vres (res, 1, true);
		  tmp = new NetEConst(vres);
		  tmp->set_line(*this);
		  delete ip;
	    } else if (NetECReal*ipr = dynamic_cast<NetECReal*>(ip)) {
		  verinum::V res;
		  if (ipr->value().as_double() == 0.0) res = verinum::V1;
		  else res = verinum::V0;
		  verinum vres (res, 1, true);
		  tmp = new NetEConst(vres);
		  tmp->set_line(*this);
		  delete ip;
	    } else {
		  if (ip->expr_type() == IVL_VT_REAL) {
			tmp = new NetEBComp('e', ip,
			                    new NetECReal(verireal(0.0)));
		  } else {
			tmp = new NetEUReduce(op_, ip);
		  }
		  tmp->set_line(*this);
	    }
            tmp = pad_to_width(tmp, expr_wid, signed_flag_, *this);
	    break;

	  case '&': // Reduction AND
	  case '|': // Reduction OR
	  case '^': // Reduction XOR
	  case 'A': // Reduction NAND (~&)
	  case 'N': // Reduction NOR (~|)
	  case 'X': // Reduction NXOR (~^)
	    if (ip->expr_type() == IVL_VT_REAL) {
		  cerr << get_fileline() << ": error: "
		       << human_readable_op(op_, true)
		       << " operator may not have a REAL operand." << endl;
		  des->errors += 1;
		  return 0;
	    }
	    tmp = new NetEUReduce(op_, ip);
	    tmp->set_line(*this);
            tmp = pad_to_width(tmp, expr_wid, signed_flag_, *this);
	    break;

	  case '~':
	    tmp = elaborate_expr_bits_(ip, expr_wid);
	    break;
      }

      return tmp;
}

NetExpr* PEUnary::elaborate_expr_bits_(NetExpr*operand, unsigned expr_wid) const
{
	// Handle the special case that the operand is a
	// constant. Simply calculate the constant results of the
	// expression and return that.
      if (NetEConst*ctmp = dynamic_cast<NetEConst*> (operand)) {
	    verinum value = ctmp->value();

	      // The only operand that I know can get here is the
	      // unary not (~).
	    ivl_assert(*this, op_ == '~');
	    value = ~value;

	    ctmp = new NetEConst(value);
	    ctmp->set_line(*this);
	    delete operand;
	    return ctmp;
      }

      NetEUBits*tmp = new NetEUBits(op_, operand, expr_wid, signed_flag_);
      tmp->set_line(*this);
      return tmp;
}

NetExpr* PEVoid::elaborate_expr(Design*, NetScope*, unsigned, unsigned) const
{
      return 0;
}

NetNet* Design::find_discipline_reference(ivl_discipline_t dis, NetScope*scope)
{
      NetNet*gnd = discipline_references_[dis->name()];

      if (gnd) return gnd;

      string name = string(dis->name()) + "$gnd";
      netvector_t*gnd_vec = new netvector_t(IVL_VT_REAL,0,0);
      gnd = new NetNet(scope, lex_strings.make(name), NetNet::WIRE, gnd_vec);
      gnd->set_discipline(dis);
      discipline_references_[dis->name()] = gnd;

      if (debug_elaborate)
	    cerr << gnd->get_fileline() << ": debug: "
		 << "Create an implicit reference terminal"
		 << " for discipline=" << dis->name()
		 << " in scope=" << scope_path(scope) << endl;

      return gnd;
}